Apr 242018
 

Southwest 1380: Micro-Aging Aircraft, Why Jack Lincoln Matters

BREAKING NEWS on April 2, 2018: A Boeing 737, performing as Southwest Flight 957, en-route from Chicago to Newark, New Jersey, carrying 73 passengers, landed safely at Cleveland’s Hopkins International Airport for maintenance on a window that cracked on the outside pane. No fatalities occurred during the aircraft’s emergency landing. The crew made the decision to divert for a “maintenance review” of a layer of the aircraft’s window pane, Southwest said Wednesday. The flight landed in Cleveland a little more than an hour after leaving Chicago’s Midway Airport, according to FlightAware.

What are the Actual Incidences of Cracked or Shattered Cockpit Windshields and Passenger Cabin Windows?

It is a Delta spokesperson’s statement on May 7, 2014 that gets folks thinking about the actual likelihood or rarity of cracked or shattered cockpit windshield or cracked passenger cabin window occurrences and such aircraft safety breaches.

In fact, cracked or shattered cockpit windshield or cracked passenger cabin window occurrences, during commercial aircraft flights at normal cruise altitudes, ranging 20-38 thousand feet, happen more often than one might think. Every week or two there is a cracked or shattered cockpit windshield incident happening on one of the nearly 90 thousands flights airborne each day (or nearly 33 million flights annually) around the world.

Remarkably, for every cracked or shattered cockpit windshield or cracked passenger cabin window incident reported, there is likely one that is not reported. International aviation safety protocols among airlines and international transport ministries have varying reporting standards of such incidents. Airlines typically do not like to widely disclose such safety breaches for obvious reasons of natural passenger and crew uneasiness, apprehension, and discomfort.

During an aircraft safety breach of a cracked or shattered cockpit windshield, as similarly during spasmodic occurrences of aircraft engine malfunctions or failures, the standard procedures in such safety breaches is for the pilots to immediately go on oxygen, and to divert the flight plan. Whereupon communication with air traffic controllers, the pilots immediately lands the aircraft at the nearest airport.

The nearly 5-6 thousand flight-cycles an airlines’ aircraft asset undergoes produces extreme thermal changes across the cockpit windshields and passenger cabin windows. This can cause moderate flight-cycle fatigue failures of the windshields, inducing face-plate and/or windshield layered construction cracks.

Above Photo Credits: via Twitter, Southwest 952 Passenger Alejandro Aguina (@Dro_AA)

Aircraft Cockpit Windshield Loading and Layered Construction

An aircraft at normal horizontal level cruise, at say 38,000 feet, like that of Delta flight 110, has four primary forces, which are: (i) an upward lift, L, (ii) a downward weight, W, (iii) a forward thrust, T, and (iv) a backward drag, D. The lift-to-drag ratio, L/D, is an aircraft aeronautical design parameter. The aircraft vehicle structural weight opposes the lift, which is also closely-aligned to the vehicle drag, D, (as an inherent function of the lift-to-drag ratio, L/D), and which is also equally-aligned to the thrust, T, (defined as a ratio of the aircraft’s fully-loaded weight, W, to the aircraft’s aeronautical design parameter, L/D).

An aircraft cockpit windshield principally carries two components of surface loads, a backwardly-directed, horizontal surface drag, d, (opposing some portion of forward vehicle thrust, T), and an upwardly-directed, vertical surface lift, v (opposing some portion of the downward vehicle weight, W).

From a materials engineering standpoint, cockpit windshields, typically weighing between 25-40 pounds, depending on the type of windshield build, are typically constructed of several layers:

(1) A glass face-plate, roughly 1/10″ thick;

(2) A Polyvinyl Butryal (PVB) layer, about 1/8″ thick;

(3) A stretched acrylic layer, approximately 1″ thick;

(4) An additional PVB layer, nearly 1/10″ thick;

(5) An additional stretched acrylic layer, approximately 1″ thick.

During a commercial flight, pilots have to heat the cockpit windshields to address the external environmental elements impacting cockpit windshields. Some aircraft will engage the window heater before descent to “soften” the acrylic layer in case of a strike. Aircraft cockpit windshields are typically designed to withstand the impact of an eight pound bird striking the aircraft front, according to Boeing aircraft engineers. Heating of the windshield makes the windshield more pliable and able to withstand an impact from a ‘bird-strike’.

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A Boeing 737-700, performing as Southwest Airlines Flight 1380 about 20 minutes into its journey from New York’s LaGuardia Airport on its way to Dallas, and carrying 144 passengers and 5 crew members onboard, made an emergency landing in Philadelphia International Airport at about 11:20am on Tuesday, April 17, 2018.

Cover Photo Credit: Taylor Lewis

This after its left CFM56 engine exploded (shown above) with engine debris flying off during a 500 miles per hour cruise-speed flight at 32,000 feet over Philadelphia, and smashing an over-the-wing window (shown below).

This immediately resulted in about a 30-45 second depressurization of the passenger cabin that pulled a woman partly out of the cabin, according to her naturally distraught family speaking to reporters. 

Fellow passengers frantically worked to yank her back inside the airliner as it depressurized and quickly descended about three thousands of feet per minute from its 500 miles per hour cruising speed and altitude of 36,000 feet, recounts a number of nearby passengers.

“The plane dropped immediately,” said Matt Tranchin, who was sitting three rows behind the broken window. “Plane smelled like smoke. Ash was all around us.” (via NBC Philadelphia News)

The late woman, who died later in a nearby Philadelphia hospital (whose family and loved ones have our sincere condolences and sympathies), was identified as 43 year old Jennifer Riordan of Albuquerque, New Mexico. She became the first and only passenger fatality on a Southwest Airlines flight in the carrier’s 51 year history. She was on a business trip for Wells Fargo, where she worked. She was pulled out of the plane up to her waist — her blood splattering other windows, passengers said.

“You hear the pop and she was sucked out from the waist up,” one passenger told NBC Nightly News. “There was blood on the windows … her arms were actually out of the airplane and her head was out of the airplane.”

According to local NBC Philadelphia reporting: “Eric Zilbert, another passenger, said “several heroic gentlemen” pulled Riordan back into the plane and immediately performed CPR. Tranchin said she was covered in blood.

Peggy Phillips, a nurse, said she and another passenger performed about 20 minutes of CPR on the victim.

“It just wasn’t going to be enough,” Phillips said.”

The heroic pilot of the Boeing 737-700, Tammie Jo Shults, as trained in the military (shown above and below today), had calmly put the airliner into a sudden dive at a controlled 3,000 feet per minute decent to a lower altitude leveling out at 10,000 feet. 

Oxygen masks dropped immediately to the faces of the rest of the 144 passengers and 5 crew members onboard terrified and strapped in their seats.

“We left LaGuardia heading to Dallas and we were west of Philly, when we lost the left side engine and diverted to Philly,” a passenger told CNN. “Shrapnel hit the window causing a serious injury (to one passenger who later died in a nearby hospital in Philadelphia). 

“We have a part of the aircraft missing,” the pilot, Tammie Jo Shults, said to Philadelphia air traffic control.

Asked whether the plane was on fire, she responded: “No, it’s not on fire, but part of it is missing. They (crew members in the cabin) said there is a hole and someone went out.”

“It definitely was a stable landing,” passenger Kristopher Johnson told CNN. “When we finally landed, it was relatively smooth. Kind of a typical landing.”

Pilot Tammie Jo Shults had performed a brilliantly cool “Sully-Like Landing on the Hudson” onto the Philadelphia International Airport runaway.

“We are aware that Southwest flight #1380 from New York La Guardia (LGA) to Dallas Love Field (DAL) has diverted to Philadelphia International Airport (PHL). We are in the process of transporting customers and crew into the terminal. The aircraft, a Boeing 737-700, has 143 Customers and five crew members onboard,” Southwest Airlines said in a released statement on Tuesday, April 17, 2018.

“We are in the process of gathering more information. Safety is always our top priority at Southwest Airlines, and we are working diligently to support our customers and crews at this time.”

“Southwest is statistically the world’s safest airline. Since starting operations in Texas in 1971, no passenger had been killed in any crash in the 51 year history of the domestic carrier (until Southwest Flight 1380, which killed one passenger),” The Independent (U.K.) reports.

“The airline, based in Dallas, is likely soon to overtake Delta to become the carrier that flies the highest number of domestic passengers.”

Reuters recently reported: “Airlines recorded zero accident deaths in commercial passenger jets last year, according to a Dutch consulting firm and an aviation safety group that tracks crashes, making 2017 the safest year on record for commercial air travel … In comparison, there were 16 accidents and 303 deaths in 2016 among airliners.”

Dutch aviation consulting firm To70 and the Aviation Safety Network both reported on January 1, 2018, there were no commercial passenger jet fatalities in 2017.

“2017 was the safest year for aviation ever,” said Adrian Young of To70.

According to Reuters: “To70 estimated that the fatal accident rate for large commercial passenger flights is 0.06 per million flights, or one fatal accident for every 16 million flights.

The Aviation Safety Network also reported there were no commercial passenger jet deaths in 2017, but 10 fatal airliner accidents resulting in 44 fatalities onboard and 35 persons on the ground, including cargo planes and commercial passenger turbo prop aircraft.”

National Transportation Safety Board chairman Robert Sumwalt and a team of investigators landed in Philadelphia Tuesday afternoon to inspect the Boeing 737-700. During a Tuesday night press conference, Sumwalt said “a part of the plane’s engine covering was found in Bernville, Pennsylvania, about 70 miles west of Philadelphia. He also said one of the engine’s fan blades was separated and missing.”

“The blade was separated at the point where it would come to the hub and there was evidence of metal fatigue,” according to Sumwalt.

Flight 1380’s engine — a CFM56 — is widely used in commercial aircraft. The $10 Million (list price) CFM International CFM56 series is “a family of high-bypass turbofan aircraft engines made by CFM International, with a thrust range of 18,500 to 34,000 pounds-force,” according to Wikipedia.

Southwest 1380 Boeing 737-700 engine’s nacelles are designed to prevent debris from breaking off the engine and flying into the fuselage. The engine will eventually be detached from the plane and taken to an off-site facility for study.

NTSB investigators are looking into why a metal fatigued fan blade on the engine caused the catastrophic engine explosion, and why the left CFM56 engine nacelle casing didn’t contain the engine debris from hitting the left wing and left-side fuselage and breaking the passenger cabin window.

Sumwalt said the NTSB investigation will be conducted for over a year.

The CFM56 engine manufacturer put out a service bulletin in the fall, telling all airlines to inspect the fan blades after a similar incident as the aircraft loss event on Tuesday involving another Southwest flight. Maintenance crews of the air carrier checked Flight 1380 on Sunday, April 22. 

According to NBC Philadelphia News: “In 2016, a Southwest Airlines flight traveling from New Orleans to Orlando diverted to Pensacola, when an engine blew out mid-flight. No injuries were reported, but the plane sustained extensive damage similar to what happened on Southwest Flight 1380 on Tuesday, April 17, 2018, as the engine’s inlet was torn away revealing additional damage to the fuselage, wing, winglet, and tail stabilizer.”

On Sunday, April 22, 2018, Southwest Airlines suspended flights of about 48 aircraft with CFM56 engines, among all flights of the carrier’s roughly 4000 Boeing 737 fleet for CFM56 engine fan blade inspections. This as the FAA on Friday called for more broader mandatory aircraft and CFM56 engine fan blade inspections for micro-cracking and high-cycle metal fatigue.

Southwest said in a news release that this move to cancel flights on Sunday comes as a part of their accelerated engine fan blade inspection program, announced on Tuesday night — not the emergency directive issued by the Federal Aviation Administration on Friday. The directive requires operators to inspect fan blades on certain engines within 20 days, according to the FAA’s website.

Southwest 1380 Fallout is Emerging Micro-Aging Aircraft and Engine Micro-cracking Detection Technologies.

Science, freedom, beauty, adventure: What more could you ask of life? Aviation combined all the elements I loved.” ─ Charles A. Lindbergh, Jr., Aviator

The advanced technology of the world’s aircraft (via, Boeing vs Airbus) manufacturers and aircraft engine manufacturers (via, United Technologies Pratt & Whitney, General Electric, and Rolls Royce) allow travelers by air to consider such extraordinary transportation as routine nowadays in their daily lives. Sixty years ago, such human mobility activities inside air transport vehicles, weighing over 750,000 pounds, and carrying 400-500 people across 6,000 miles of land and sea at 500-650 miles per hour, was unthinkable.

According to a November 2016 FAA report entitled, “The Economic Impact of Civil Aviation on the U.S. Economy,” “American aviation means so much for so many people. Things like safety, security, efficiency, freedom, adventure and commerce come to mind. Aviation accounts for more than 5% of our Gross Domestic Product (GDP), contributes $1.6 trillion dollars in total economic activity, and supports nearly 11 million jobs. Aviation manufacturing continues to be the nation’s top net export (as one of the few scientific and technological positive balances of global trade for America).”

Photo Credit: Wikipedia. “Aloha Airlines Flight 243 (IATA: AQ243, ICAO: AAH243) was a scheduled Aloha Airlines flight between Hilo and Honolulu in Hawaii. On April 28, 1988, a Boeing 737-297 serving the flight suffered extensive damage after an explosive decompression in flight, but was able to land safely at Kahului Airport on Maui. There was one fatality, flight attendant Clarabelle Lansing, who was ejected from the airplane. Another 65 passengers and crew were injured. The safe landing of the aircraft, despite the substantial damage inflicted by the decompression, established Aloha Airlines Flight 243 (like the Southwest Airlines Flight 1380 incident on Tuesday, April 17, 2018as significant events in the history of aviation, with far-reaching effects on aviation safety policies and procedures.”

We need to rebuild our “Fast Transportation Infrastructure Technology” to keep up with our now “Fast Growing Economy,” so we can put our “Fast Capital” to work and create JOBS, JOBS, JOBS, especially to unite rural and urban regions across this country.

So, here’s how government, university, and industry partners inside the micro-aging aircraft research community are responding. 

First of all, Aging Aircraft Conferences, including the 2018 Aircraft Airworthiness and Sustainment Conference, address sustainability and structural integrity concerns that have significantly escalated in the micro-aging of military aircraft, space vehicles, and commercial aircraft fleet in the past decade. These technical conferences focus on safety of micro-aging aircraft operating near or beyond their original design service criteria. Also addressed are conventional aging aircraft issues alongside aircraft fleet life cycles, and new aircraft entering the fleet with advanced materials and structures and advanced manufacturing technologies.

Still further, the 2018 Engine Propulsion Safety and Sustainment Conference brings together government, academic, and industry representatives, who are addressing advanced turbine engines technologies used in space vehicles, military aircraft,  and commercial passenger aircraft aimed at improving performance and operability, reducing engine mishaps, maintenance costs, and increasing average service time on the aircraft wing.

I attended the 2017 Aircraft Airworthiness and Sustainment Conference and the 2017 Engine Propulsion Safety and Sustainment Conference held at the Sheraton Downtown Hotel in Phoenix, Arizona on May 22-25, 2017.

Thereat we’ve learned that crack detection and statistical assessments of damage tolerant design of aircraft structures and engines is a quantitative measure of our capacity of nondestructive evaluation inspection technologies (including fluorescent penetration, eddy currents and ultrasound) to detect flaws. These techniques provide mathematical statistical input to probabilistic fracture science and mechanics to estimate the probability that a structural flaw or micro-crack could go undetected in manufacturing, installation, and maintenance of aircraft engines or main aircraft structures (wings, fuselage or tail section). 

Such mico-aging or micro-cracking detection technologies have been in place for several decades and employed by the United States Air Force in its Engine Structural Integrity Programs, which has been adopted by the Micro-Aging Aircraft research community and industrial firms, such as Lockheed Martin, Boeing, Airbus, General Electric, United Technologies Pratt & Whitney, and Rolls-Royce.

The need remains acute for standardized procedures, criteria, innovative methodologies for recognition of aircraft structures and aircraft engine micro-aging inspections, and fundamentals of flaw detection systems capabilities affected by these three detection factors in aircraft engines parts, particularly:

(1) new materials design (and blade subsurface inhomogeneity associated with powder metallic and titanium blades and integrated bladed rotors, even in the future involving emerging micro-nano architectured-material additive manufacturing 3-D printing technologies);

(2) fatigue cracks, scratchesflaw or defects (because not all scratches are critical, and not all flaws and defects are created equally);

(3) parts design considerations and inspection conditions ─ USAF, DOD, FAA, Lockheed Martin, NASA, and Deloitte are leading the evolution of additive manufacturing as a promising new tool in the application, maintenance and safety of aircraft engines parts. Re-engineering is often required to use additive manufacturing to make a load-bearing, fatigue critical replacement part. This emerging parts design and inspection technology has implications for aircraft airworthiness and sustainability of aircraft propulsion systems.

Micro-aging Aircraft research and development is also driven nowadays by real parts micro-crack detection technologies for aircraft structures and engines technical communities. Real parts micro-crack detection is extremely complex, because it is influenced by these four aspects: 

(1) material properties ─ composition, heat treatments, and cleanliness of the material of engine parts;

(2) flaw or defect characteristics ─ character, size, shape, and location of engine parts flaws or defects;

(3) design and manufacturing considerations ─ accessibility, surface condition, and repairs of engine parts;

(4) inspection conditions ─ such as lighting and temperatures.

This allows aerospace scientists and engineers to share fracture science and mechanics technology and airframe and engines structural integrity experience to best arm FAA regulators with better damage tolerance guidance, particularly in the area of nondestructive evaluation systems development and implementation. 

This also calls for ongoing needs in micro-aging and micro-cracking detection models of parts, capacity building of inspection equipment and techniques, and improved methods of measuring inspection systems capabilities. 

Overarching above all this is the urgent need for synergy among government, universities, and industry to create complete organizational integration of parts quality, manufacturing, and engineering for field implementation of laboratory-developed inspection systems across the Micro-Aging Aircraft community.

Micro-aging of Aircraft is an Established Engineering Science. 

Evolving over four decades has been the United States Air Force (USAF) Aircraft Structural Integrity Program (ASIP). Below are the United States Department of Defense F-22 ASIP Case Study Lessons Re-Learned in the fallout of the recent Southwest Flight 1380 crash landing from micro-cracking of its aircraft engine fan, which led to the Boeing 737-700 Aircraft Structural breach from an engine “fan blade debris salad” spread, killing one woman fatally impacted by the sudden passenger cabin decompression for a horrific 30-45 seconds.

Looking back in history, the original national research and development solicitation for the Advanced Tactical Fighter (ATF) was issued by the USAF in July 1986. At that time back in the Reagan Administration locked-in an escalating arms race with the former Soviet Union, a new air superiority fighter was needed to strategically compete with emerging Soviet fighter capability (Su-27, MIG-29), and to effectively replace the F-15 and F-16 military fighter fleet.

In April 1991, a United States Defense Department contract was awarded to a joint-industrial partnership between Lockheed Martin, General Dynamics, and Boeing.

The F-22 aircraft specification included “durability and damage tolerant design tasks” (including structural micro-cracking of aircraft engines and structural micro-aging of aircraft frame systems) laid out in a seminal 1975 USAF Report on “Aircraft Structural Integrity,” originally outlined by The Late Jack Lincoln (see Appendix). This report also serve to task the United States Federal Aviation Administration’s Aircraft Safety Oversight for the next four decades.

F-22 design was fully compliant with Aircraft Structural Integrity Program requirements in structural fracture mechanism and controls (considering parts durability, micro-aging damage tolerances, micro-cracking propagation science, and aircraft structural sizing criteria ─ established at the Aircraft Structural Integrity Program’s inception ─ alongside fail-safe design requirements for damage tolerant micro-mechanical (and even nano-mechanical and genomics of) materials, and for probabilistic mechanics approaches for solutions of micro-aging aircraft concerns.

Photo Credit: John W. Lincoln, “Risk Assessments – USAF Experience,” Aeronautical Systems Division of USAF/AFSC, Proceedings of the International Workshop on Structural Integrity of Aging Airplanes, March 31 – April 2, 1992, Atlanta, Georgia.

DOD, USAF, and FAA overall aircraft safety risk assessment goals over the next four decades to today have been guided by a “determination of the probability of failure of an aircraft selected at random from a population of similar aircraft. The primary result of the calculation is the single flight probability of failure. This is the probability that failure will occur on a single flight of an aircraft selected randomly from the population. From this, the probability of failure after a given time and the expected number of aircraft losses may be determined” ─ in Jack Lincoln’s own words in describing the USAF’s experience in aircraft risk assessments back in 1992.

 

Photo Credit: John W. Lincoln, “Risk Assessments – USAF Experience,” Aeronautical Systems Division of USAF/AFSC, Proceedings of the International Workshop on Structural Integrity of Aging Airplanes, March 31 – April 2, 1992, Atlanta, Georgia.
 
Since then, micro-aging aircraft risk assessments have been the standard protocol on numerous USAF aircraft, including “the B-52 Wing, KC-135 wing, C-5A wing, C-141B fuselage and wing, F5 fuselage, T-38 fuselage and wing, and the T-37 complete aircraft,” according to Dr. Lincoln. 
 
The USAF generally concludes “for military aircraft that a single flight probability of 1 in a millionth or less is adequate for long term operations.” If this extremely low probability number is multipled by the size of the military aircraft fleet (or even by the size of Southwest Airlines’ commercial passenger exclusively Boeing 737 fleet for about 4000 flights a day), consequently, an expected level of aircraft loss events may be reasonably estimated.
 
Imagine these astronomical odds for the commercial passenger Boeing 737 performing as Southwest Flight 1380! Crash landing this aircraft was the work akin to Scully’s Landing on the Hudson in New York City.

The Aircraft Structural Integrity Program (ASIP) dates back to a 1950’s Air Force publication on structural integrity requirements. It was known from an early stage that ASIP was a vital program in prolonging the life and ensuring the structural safety of all aircraft. Meetings began in the 1970’s, but it wasn’t until 1984 that it was reshaped into the current conference format. Incidents like the 1988 Aloha Flight 243 Air Disaster highlighted the importance of ASIP requirements and the contributions of the ASIP community, to preclude the recurrence of such tragedies in the future. The ASIP Conference helps to accomplish this through the personal interactions of its attendees, resulting in the exchange of vital ideas and technology. In 1996, the ASIP Committee established the Lincoln Award to recognize individuals who have made significant contributions throughout their distinguished careers to ensure the structural integrity and safety of our aircraft.

Why John (Jack) W. Lincoln, Ph.D., P.E. (1928 – 2002) Matters!

Credit: Aircraft Structural Integrity Program (ASIP) Conference, November 26-29, 2018, Downtown Hyatt Regency Phoenix, Arizona.

The Accomplishments of Dr. John (Jack) W. Lincoln

“Dr. John (Jack) W. Lincoln is still recognized internationally as an expert in structural integrity and a champion of aviation safety. From his early days as an aviator, piloting a DC-3 aircraft for his father’s Dallas, Texas based “Lincoln Airlines,” his contributions as Chief of Structures at Vought Aerospace, to his career with the United States Air Force (USAF), Dr. Lincoln was a pioneer in aerospace engineering.

Dr. Lincoln is credited with maturing the Aircraft Structural Integrity Program (ASIP) into a robust process that is now institutionalized within the Air Force and recognized worldwide as the model for ensuring aircraft structural airworthiness. The USAF’s unparalleled worldwide aircraft structural safety record since 1980 is directly attributable to Dr. Lincoln’s leadership in the field of structures technology.

In 1971, Dr. Lincoln brought 22 years of structural design experience from Vought Aerospace to the Aeronautical Systems Division (ASD) of the United States Air Force at Wright-Patterson Air Force Base and accumulated another 29 years of service to both military and commercial structural integrity processes over his distinguished career. Dr. Lincoln’s initial assignment with the Air Force in 1971 was to direct an independent review of the C-5A aircraft. This work determined the structural modifications required to achieve the originally planned service life for this aircraft. For his outstanding contributions in this area, Dr. Lincoln was awarded the 1973 USAF Meritorious Civilian Service Medal. During his career in the Air Force, he has influenced the design of many aircraft including the C-5B, B-1B, F-15E, F-16, T-46, C-17, F-22 and Joint Strike Fighter.

As a Technical Expert and then Technical Advisor for Engineering, he directed the execution of damage tolerance assessments for many of the USAF major aircraft weapon systems. This effort defined the inspection, maintenance, repair and modification programs required to maintain flight safety of each of these aircraft. Dr. Lincoln participated in a multitude of engine damage tolerance assessments and was the driving force behind development of the damage tolerance approach for Air Force helicopters.

Dr. Lincoln worked tirelessly with leaders in the military and commercial aerospace technology arena and developed industry standards for transition of new structural technologies to full-scale development. He served as an advisor and principal participant in ad hoc panels of the United States Air Force Scientific Advisory Board addressing structural integrity issues on systems including the C-5A, KC-135, C-130 and the C-141.

In the interest of commercial aviation safety and the advancement of damage tolerance principles, he worked extensively with the Federal Aviation Administration (FAA), acting in a capacity as a senior technical advisor. Dr. Lincoln’s affiliation with and contributions to the FAA spanned many years. For example, in 1979 at the request of the FAA, he led the damage tolerance assessment by Douglas Aircraft Company of the DC-10 pylon following the crash of a DC-10 at Chicago, Illinois. His findings and recommendations permitted the FAA to identify the cause of failure and institute a maintenance program that would preclude a reoccurrence of this problem in the future.

Dr. Lincoln was an active member of the FAA sponsored Technical Oversight Group on Aging Aircraft (TOGAA). This group was charged with examining the problems of aging in the commercial fleet and advised the FAA on design and maintenance actions required for aircraft ranging from small commuter class to large transports. Dr. Lincoln drafted rules for the application of damage tolerance to commuter aircraft design. As a part of the effort with TOGAA, he has established guidelines for the continued airworthiness of commuter class aircraft.

USAF Career Highlights

In 1972, amidst significant public debate over structural shortfalls in the Air Force’s newest transport aircraft, the C-5A Galaxy, Lieutenant General Stewart, commander of the Aeronautical Systems Division, requested that Dr. Lincoln lead an Independent Review Team (IRT) for that program. The IRT was a major challenge since the hundred people composing the independent team, recruited from all over the United States and the United Kingdom, had no previous experience with this aircraft. Further, damage tolerance procedures were developed and applied to the C-5A by the IRT under the direction of Dr. Lincoln, the first application of these procedures to a transport aircraft and thus formed the basis for future aircraft damage tolerance assessments undertaken by the USAF. The culmination of this one-year effort included a briefing by Dr. Lincoln to the Secretary of the Air Force where he successfully championed the IRT recommendations for the C-5A program modifications.

In a follow-on evaluation in 1979, Dr. Lincoln chaired the C-5A Structural Information Enhancement Program. Dr. Lincoln pioneered a new application of aircraft inspection data, structural testing and fail-safe analysis in the use probabilistic software he developed to perform a risk analysis and made projections for the onset of widespread fatigue damage in the fleet. The results of his evaluation permitted the Air Force to continue safe operations with limitations until wing replacements could be implemented. Dr. Lincoln’s impact on this system survives today with the decision to extend the operational life of the C-5A by another 20 years.

During the period from 1975 to 1990, he directed the damage tolerance assessments of many of the major weapon system in the USAF inventory. These efforts involved all major aerospace manufacturers and included multidiscipline structural analysis representing over a million man-hours of work. In addition to providing the Air Force critical information on operational utility, this effort defined and implemented individual aircraft tracking programs based on damage tolerance principles. This approach to fleet management is a mainstay in Air Force aircraft fleet management and a principal basis for the operational safety record enjoyed by the USAF. The work performed by Dr. Lincoln during this period made possible a significant life extension program for the KC-135 and provided critical information in the decision to perform major upgrade modifications on the C-141 and B-52 programs. Dr. Lincoln served as a member of the steering group for damage tolerance assessments of the F100 and TF34 engines. These assessments were pioneering efforts that established the procedures for many engine damage tolerance assessments that followed in both the military and commercial worlds.

He served as chairperson of the F-15 Structural Review Committee. This committee investigated the cause of an in-flight wing failure from overload and provided oversight on activities relating to fatigue problems on the vertical tail and wing. This activity led to the development and implementation of damage tolerance criteria on the F-15 and resolution of the F-15 buffet issues that had caused numerous failures in the vertical tail.

In 1986, he led an independent review of the T-37 aircraft to determine the modifications needed to permit this aircraft to remain in operational service for an additional fifteen years. Again, he applied the probabilistic methods he had developed in a risk assessment of the aircraft structure, permitting continued fleet operations with provisions for inspections.

He served as chairperson of a review team in 1988 to assess the impact of a full-scale static test failure of the F-16 wing. Performing a risk assessment of the aircraft based on data from operational aircraft, he provided rationale for a redesign to restore the aircraft to its original static strength requirement.

He served on a National Aeronautics and Space Administrative (NASA) committee for the certification of hypersonic vehicles. This activity led to the establishment of a specification for a facility to perform hypersonic testing of aircraft such as the National Aerospace Plane. It also served to introduce damage tolerance requirements in the design of spacecraft.

In response to a 1990 request from Mr. Jack Welch, Secretary of the Air Force for Acquisition, he performed an independent study on the structural modification program for the F-16 aircraft. This effort was difficult because of the early cracking of aircraft that had seen operational usage approximately eight times more severe than the design usage. This effort provided senior Air Force leadership with the assurance that the aircraft needed these modifications and also gave them an independent assessment of the costs of implementing them.

In response to a 1991 request from Major General Gillis, Commander of the Warner Robins Air Logistics Center, Dr. Lincoln performed a risk assessment of the C-141 structural wing containing multi-site fatigue damage type cracking. Dr. Lincoln’s risk assessment involved the assessment of the airworthiness of cracked (a) span-wise splices, (b) wing plank weep holes and (c) multiple critical structural frames. His analysis identified repair, replacement and inspection options for maintaining the safety of the C-141 aircraft during the Desert Shield/Desert Storm conflict and permitted the full operational capability of the aircraft to be used. He briefed his findings to General Johnson, Commander of the Air Mobility Command, which resulted in an extensive inspection program. In a follow-on Scientific Advisory Board Review, Dr. Lincoln’s recommendations on implementation of recently developed composite patching of the wing skins on the C-141 were accepted and the fleet was restored to full operational capability. Without Dr. Lincoln’s efforts, the complete C-141 fleet would have been grounded. Subsequently, Dr. Lincoln responded to a request by the Department of Defense (DOD), and conducted an independent assessment of the remaining life of the C-141 aircraft. His findings and recommendations were used in the decision to press forward with the development of the C-17 as a future replacement aircraft.

At the request of Lieutenant General Fain in 1992, he served as leader of the USAF team working with the US Navy to develop the Joint Structures Specification Guide. These criteria served as the principal guidance for contemporary USAF and Navy aircraft design. He was the Senior Civilian Participant in an USAF Scientific Advisory Board Summer Study in 1994; tenets developed by Dr. Lincoln were briefed to the Chief of Staff and served as the basis for aging aircraft research and development.

At the request on Major General Franklin, Program Executive Officer (PEO) for the C-17, he acted as senior advisor in the executive independent review of the C-17 test wing failure that occurred in 1992. He briefed his findings and recommendations to Secretary of the Air Force and the Chief of Staff. His input and the work of this committee outlined a recovery plan that resulted in the successful retest of a modified wing.

In 1995 he chaired an independent review team assessment of F-16 service life. The review determined actions required to ensure that the aircraft could reach its 8,000-life goal. Included was a recovery action for the significant cracking being experienced in the fuselage bulkhead that supports the vertical tail.

Contributions to Commercial and International Aviation

At the request of the FAA, Dr. Lincoln performed an independent assessment of the Boeing 747 structure in 1987. His evaluation led to a series of detailed inspections of the aircraft in prescribed locations. In 1979 he oversaw the damage tolerance assessment performed on the DC-10 engine pylon following the mishap of a DC-10 in Chicago, Illinois. Dr. Lincoln served as a tenured member of the TOGAA chartered by the FAA after the highly publicized 1988 Aloha Airlines incident. Dr. Lincoln’s work in this group focused on issues of widespread fatigue damage in commercial aircraft. In support of the evaluation of the Aloha incident, Dr. Lincoln helped formulate the Airworthiness Directives permitting safe operations of both the 737 and the 727. In 1990, following the in-flight structural failure of the DC-10 engine resulting in the mishap at Sioux City, Iowa, he was called on for his technical expertise in the development of a recovery plan for the material issue that contributed to the engine disc failure.

As a senior technical advisor with the TOGAA, Dr. Lincoln advised the FAA on research and development initiatives related to aging commercial aircraft. His interaction with researchers at Iowa State University, Wayne State University, The Johns Hopkins University, Northwestern University and Sandia National Laboratory resulted in significant technological gains in the area of non-destructive inspection techniques. He wrote the Advisory Circular for the FAA Administrator for Certification and Regulation, which serves as the standard for the structural integrity of commuter class aircraft operated in the United States. His technical expertise was key in the development of a recovery program for the hard alpha problem, which is a material contamination issue in the titanium engine disc, that caused the crash of the DC-10 at Sioux City, Iowa.

Starting in 1990, Dr. Lincoln figured prominently in the work of the International Committee on Fatigue (ICAF), presenting papers recognized internationally for their contribution to aircraft structural integrity. In this forum, he shared his extensive knowledge of aircraft damage tolerance, probabilistic methods, technology transition, widespread fatigue damage in aircraft, full-scale aircraft structural testing and aircraft repair concepts. He has been acknowledged as an international expert in his field by aircraft structural experts from Australia, Canada, France, Germany, Israel, Italy, Japan, The Netherlands, Sweden, Switzerland, the United Kingdom, and the United States. In 1997, Dr. Lincoln was awarded the F.J. Plantema Award, the highest international honor for contributions for solving structural fatigue issues, by unanimous vote of the delegates of those nations forming the ICAF, and he was the plenary speaker at their conference.

He was a member of The Technical Cooperation Program (TTCP) AER-TP4 Panel Structures and Structural Dynamics and MAT-TP8 Panel on Composite Materials. The TTCP is a cooperative program among Australia, Canada, New Zealand, the United Kingdom, and the United States. In this capacity, he has acted as the principal contributor to specifications for the use of composites in aircraft structures.

He was a prominent member of the North Atlantic Treaty Organization (NATO), Advisory Group for Aerospace Research and Development (AGARD) and later RTO Advanced Vehicles Technology Panel. He presented his works on probabilistic methods and structural integrity to international experts in Lindau, Germany, Bath, United Kingdom, Bordeaux, France, and Rotterdam, the Netherlands. At the request of the FAA and NASA, he was a long-standing member of the organizing committee of FAA/NASA international meetings forum.

Beginning in 1984, Dr. Lincoln served as chairperson of the annual Aircraft Structural Integrity Program Conference and as host to domestic and international aerospace experts promoting military and commercial aircraft structural integrity. In 1996, Dr. Lincoln was recognized for his lifelong contributions during the annual international ASIP conference by being selected as the first recipient of the Dr. John W. Lincoln Award. This record is spectacular in view of the fact that many of the aircraft in the USAF inventory have flown safely well beyond their original design service life and continue to meet the United States’ vital military missions.

The South Korean government solicited Dr. Lincoln’s assistance in 1995 in assessing the viability of their new trainer. He proposed and the government adopted his recommendations on structural integrity actions. Also in 1995, Israeli Air Force (IAF) requested Dr. Lincoln’s support in addressing several structural issues with aircraft mechanical systems. His recommendations led to a cooperative USAF/IAF development program that substantially enhanced mechanical system integrity.

Summary

Dr. Lincoln was a highly respected engineer, recognized both nationally and internationally, for his outstanding knowledge of structural technologies and probabilistic risk assessment methods for ensuring aircraft airworthiness. His legacy as a pioneer in the field of structural integrity and damage tolerance has undoubtedly made a significant contribution to the continuing airworthiness and safety of military and commercial fixed and rotary wing aircraft and engines. Dr. Lincoln influenced foreign and domestic commercial and military aircraft development through industrial and/or governmental agency representatives and through organizations such as NATO, TTCP, ICAF and the FAA.

He was a leader in his field and a mentor to aspiring young engineers and maintenance personnel. Through his vision, demeanor and leadership he guided and greatly influenced the design and maintenance philosophy of today’s aircraft. In particular, his technical expertise was critical to the development of maintenance policies and operation of United States Air Force aircraft. Dr. Lincoln’s enduring legacy continues to advance the engineering sciences that are essential to prolonging the safe operational life of our military fleet of air vehicles. In his work in both commercial and government sectors, he made substantial contributions to the structural integrity of over fifty-five aircraft and missiles.

Dr. Lincoln was internationally recognized for his work in structural integrity and probabilistic risk assessment methods. In 2005, the revision of the Department of Defense’s MIL-STD-1530C (ASIP) incorporated Dr. Lincoln’s probabilistic risk assessment concepts and criteria so that his approaches would be promulgated and provide direction to those responsible for ensuring the initial and continuing airworthiness of aircraft and missile structures.

Thanks to Dr. Lincoln’s influence, the area of Structural Fatigue and Risk Analysis techniques, the USAF’s record of structural failures in flight has gone to near zero. This has also translated into near zero structural failures in flight in the commercial world, even though some of the aircraft are well over 60 years old and are still flying revenue passengers. Finally, even though Dr. Lincoln’s work has been in the aircraft structures, it has seen global applications in areas such as trucks and cars.“

Previous Lincoln Award Winners

Year Lincoln Award Winners

2017 Mr. Robert J. Burt

2016 Dr. Anders Blom

2015 Mr. Ed Ingram

2014 Mr. Larry Perkins

2013 Dr. Thomas R. Brussat

2012 Mr. James L. Rudd

2011 Mr. Len Reid

2010 Professor Graham Clark

2009 Mr. Robert M. Bader

2008 Dr. Joseph P. Gallagher

2007 Dr. Alan P. Berens

2006 Dr. Ulf G. Goranson

2005 Mr. Charles R. Saff

2004 Mr. Robert Bell

2003 Mr. Ward Rummel

2002 Mr. Royce Forman

2001 Prof. James C. Newman, Jr.

2000 Prof. Alten Grandt, Jr.

1999 Prof. Jaap Schijve

1998 Mr. Thomas Swift

1997 Mr. Charles F. Tiffany

1996 Dr. John W. Lincoln

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About The Author

Oliver G. McGee III is a teacher, a researcher, an administrator, and an advisor to government, corporations and philanthropy. He is former department chair (2016-17) and professor of mechanical engineering at Texas Tech University. He is former professor of mechanical engineering and former Vice President for Research and Compliance (2007-08) at Howard University. Dr. McGee is former Senior Vice President for Academic Affairs of the United Negro College Fund (UNCF), Inc. He was Professor and former department chair (2001-2005) of the Department of Civil & Environmental Engineering & Geodetic Science at Ohio State University. He is the first African-American to hold a professorship and a departmental chair leadership in the century-and-a-quarter history of Ohio State University’s engineering college. Dr. McGee has also held several professorships and research positions at Georgia Tech and MIT.

McGee is the former United States (U.S.) Deputy Assistant Secretary of Transportation for Technology Policy (1999-2001) at the U.S. Department of Transportation (DOT) and former Senior Policy Advisor (1997-1999) in The White House Office of Science and Technology Policy. He is a NASDAQ certified graduate of UCLA John E. Anderson Graduate School of Management’s 2013 Director Education and Certification Program, and NYSE Governance Services Guide to Corporate Board Education’s 2003 Directors’ Consortium (on corporate board governance).

McGee is a 2012-13 American Council on Education Fellow at UCLA Office of the Chancellor Gene Block. He is a 2013 University of California Berkeley Institutes on Higher Education (BIHE) graduate. He is also an Executive Leadership Academy Fellow of the University of California, Berkeley Center of Studies in Higher Education (CSHE) and the American Association of Hispanics in Higher Education (AAHHE), Inc. McGee is an American Association of State Colleges & Universities’ (AASCU) Millennium Leadership Initiative (MLI) Fellow – educational leadership and management development programs for prospective university chancellors and presidents.

Education Background: Ohio State University, Bachelor of Science (B.S.) in Civil Engineering, University of Arizona, Masters of Science (M.S.) in Civil Engineering, University of Arizona, Doctor of Philosophy (Ph.D.) in Engineering Mechanics, Aerospace Engineering (Minor), The University of Chicago, Booth School, Masters of Business Administration (M.B.A.), The Wharton School, University of Pennsylvania, Certificate of Professional Development (C.P.D.), Indiana University Lilly Family School of Philanthropy – Certificate of Fund Raising Management (C.F.R.M.).

Partnership Possibilities for America – Invested in STEEP Giving Forward, founded by McGee in 2010, is based in Washington, DC.

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