Oct 302015

Dynamic Airways B767-200ER N251MY FLL

A Pratt & Whitney JT9D-7R4D left turbofan engine burst into flames on a taxiing Dynamic International Airways Boeing 767-200ER, carrying 101 passengers and flight crew, just prior to its departure at Fort Lauderdale-Hollywood International Airport (in Dania Beach, Florida USA) en route to Caracas, Venezuela. 

Photo Credit: Flicker.com, Dynamic Aviation Group Boeing-767-300ER, Registration Number N251MY

The 29-year-old Boeing 767-200ER airliner, Registration Number N251MY, operating as flight 2D-405 on Thursday, October 29, 2015, was taxiing on the ground before departure at about 12:34pm ET, holding short of Fort Lauderdale Airport’s runway 28R after contacting the local air traffic control tower.

Suddenly, the flight crew of another aircraft, taxiing behind Dynamic International Airways flight 2D-405, advised the flight deck of the Boeing 767-200ER airliner that there was a massive Jet A-1 fuel leak from the left Pratt & Whitney turbofan engine (JT9D-7R4D).

Pratt & Whitney developed the first high bypass ratio turbofan engine (JT9D-7R4D) to power a wide-body airliner, originally designed for application to the first Jumbo Boeing 747-100 airliner.

Boeing 767 Fort Lauderdale Fire

Immediately, the flight deck of the Boeing 767-200ER airliner acknowledged the fuel leak and then requested to return to the ramp.

That was when the other advising flight deck airliner, taxiing behind flight 2D-405, alerted the Boeing 767-200ER flight deck that the new condition of their aircraft was their left turbofan engine was now on fire!

Boeing 767 Fort Lauderdale Fire 2

According to Reuters, at 12:34pm ET the Boeing 767-200ER airliner was evacuated via slides in about 3 minutes. 

Luis Campana, a 71-year-old rancher, along with his wife and sister, were three of the 101 passengers and crew on-board Dynamic International Airways flight 2D-405 traveling to Venezuela’s Guarico state.

“It was a real scare,” Campana told Reuters at Fort Lauderdale-Hollywood International Airport. He said, “he had been sitting near the front of the plane, as the pilot put the thrust on to taxi up the runway.”

“The engine exploded. As we were getting out of the plane down the chute, the smoke was beginning to enter and the engine was in flames,” he said.

Twenty-one people were injured, one seriously, most of whom were treated at a hospital and released, said Broward Sheriff Fire Rescue spokesman Mike Jachles.

Don Dodson, the director of operations for Dynamic Airways, said airline officials had set up a crisis center, flown in additional airline representatives to help passengers and arranged for a relief flight to take passengers to their final destinations.

Emergency services responded in two minutes at 12:36pm ET, according to Mike Jachles of the Boward County Fire Rescue, upon which firefighters extinguished the fire using foam seven minutes later at 12:41pm ET.

The National Transportation Safety Board has initiated its investigation of the Boeing 767-200ER fire that injured several passengers on the tarmac at the South Florida airport Thursday, according to Greg Meyer of the Boward County Aviation Department.

The plane had no previous incidents or issues, the Federal Aviation Administration said.

The Boeing 767/269 — manufactured in 1986 and owned by Utah-based airplane leasing company KMW Leasing in Salt Lake City — lost 45 to 50 gallons of fuel, damaging the asphalt. Taxiway repairs should be complete later Friday or Saturday, Fort Lauderdale/Hollywood International Airport Director Kent George said (via Fox News).

“More than 100 passengers had to evacuate using emergency slides. Some ran from the plane into the terminal as fire crews rushed to put the fire out,” Fox News reported.

Kent George, Director of the Broward County Aviation Department, said (via Fox News), “the flames never entered the cockpit.”

Dyanmic Airways Logo

Dynamic International Airways, according to the limited liability company founded in 2008, is a certified Part 121 Carrier, operating fleet of seven Boeing 767-200ER aircraft that typically carries up to 250 people. The air carrier is based in Greensboro, North Carolina that connects Fort Lauderdale, New York, Venezuela and Guyana.

In past Dynamic International Airways operated mostly for other carriers and tour operators under their wet lease agreements.

In 2014 the airline started its own passenger service on multiple international markets including China, Saipan, Guam, Hong Kong, Guyana and Brasil.

Only recently, Dynamic International Airways announced it has launched its low-cost service between Fort Lauderdale, Florida and Caracas, Venezuela.

“For Venezuelans hoping to travel abroad, the options have been severely reduced to little-known carriers such as Dynamic or domestic carriers, which due to the country’s economic crisis, have struggled to import replacement parts,” according to Fox News.

Boeing 767 Fort Lauderdale Fire 3 - Fuel Leak Causes Engine Fire on Boeing 767 Prior to Takeoff in Florida

Photo Credit: AP Photo/Wilfredo Lee. “Firefighters walk past a burned out engine of a Dynamic Airways Boeing 767, Thursday, October 29, 2015, at Fort Lauderdale-Hollywood International Airport in Dania Beach, Florida. The passenger plane’s engine caught fire Thursday as it prepared for takeoff, and passengers had to quickly evacuate on the runway using emergency slides, officials said. The plane was headed to Caracas, Venezuela.”
How we all can relate to this Dynamic International Airways Boeing 767 engine safety breach? 
Immediate question among the flying public is whether it is indeed safe to fly given today’s rare engine safety circumstances, surrounding the departure of Dynamic International Airways flight 2D-405.
The answer is yes, of course, supported by a poignant U.S. federal government statistics.
For air and space transport (including air taxis and private flights), the National Safety Council (NSC) says the relative risks of flying are extremely favorable odds of 1 in 7,178 for a lifetime against one receiving death or injury as a result of flying in a commercial passenger airliner. These relative risks of flying are compared by the NSC to the odds of dying in a motor vehicle accident at 1 in 98 for a lifetime, the USA Today reports.
Be that as it may, my father was a firefighter. He impressed upon me that firefighters and ground crews at these airports must work fast to put such hot fires out, as a result of exploding Jet A-1 engine fuel, having a flash point greater than 38 degrees Celsius (100 degrees Fahrenheit), with an autoignition temperature of 210 degrees Celsius (410 degrees Fahrenheit).
Dynamic International Airways Boeing 767-200ER’s engine fire today on the Fort Lauderdale-Hollywood International Airport runway was an extremely hot Jet A-1 engine fuel fire at burn temperatures reaching as high as 2,500 degrees Kelvin (2,230 degrees Celsius, or 4,040 degrees Fahrenheit), including open air burn temperatures climbing as high as 1,030 degrees Celsius, or 1,890 degrees Fahrenheit.
Moreover, fast cabin evacuation inside the Dynamic Airways’ Boeing 767-200ER of all the 101 passengers and crew was remarkably achieved in three minutes or 180 seconds – about twice the 90 seconds mandated by FAA regulations – that fortunately saved the lives of all passengers and flight crew on-board flight 2D-405.
So today, congratulations goes out to the Dynamic Airways 2D-405 flight crew for their fine execution of passenger evacuation of the cabin at the moment of the flight deck determination of a fire inside the left Pratt & Whitney JT9D-7R4D turbofan engine.
Additional salute goes out to the Fort Lauderdale-Hollywood International Airport ground crews and controllers, as well as, some heads up eyewitness warning on the ground (from the flight deck of a nearby taxiing airliner) of leaking Jet A-1 fuel from that Boeing 767-200ER’s left turbofan engine causing this massive fire and thick black smoke bellowing high into the sky (shown via Reuters below).

Boeing 767 Fort Lauderdale Fire - Fuel Leak Causes Engine Fire on Boeing 767 Prior to Takeoff in Florida

We can all emotionally recall, we had seen a similar massive fire with thick black smoke bellowing high in the sky, resulting from extremely hot Jet A-1 engine fuel inside the World Trade Center fire fourteen years ago on 9-11-2001.  

Therein, that tall building’s constructed steel melted, when it reached  a temperature of 800 degree Fahrenheit, as a result of forced mixing with a highly flammable Jet A-1 engine fuel, which burns at an extremely hot temperature approaching 2000 degrees Kelvin.

When Jet A-1 fuel burns uncontrollably, it induces a thick bellowing cloud of black smoke. 

WTC Tower on 9-11
Photo Credit: “It is an easily verifiable truth that Flight 175, as the Boeing 767 that it was, carried two Pratt and Whitney JT9D-7R4D turbofan engines run on hot Jet A-1 engine fuel. “Flight 11” struck the North Tower –as seen above– at 8:46 AM. “Flight 175” struck the South Tower at 9:03 AM. At that moment upon hitting the South Tower, the flaming Pratt and Whitney JT9D-7R4D engine fell onto the street below landing broken apart at the corner of Church and Murray Street in lower Manhattan.
Unfortunately, fast evacuation from tall buildings is much tougher and slower, than fortunately, the faster evacuation from commercial aircraft – mandated by FAA to be under just 90 seconds!
So, air passengers please read those seat-back cards in front of you that the flight attendants are instructing you to do during pre-flight safety procedures. 
Most of all, do determine in your mind your nearest route to an exit, including your emergency evacuation plan. 
Those passengers seated at the exits are federally-required by law to assist all passengers and flight crew in the event of an emergency evacuation of all commercial passenger aircraft.
An additional truth about rare sudden aircraft turbofan engine fires is that we are extremely lucky the Dynamic Airways Boeing 767-200ER’s Pratt & Whitney JT9D-7R4D turbofan engine fire did not occur later upon takeoff. 
Therein, the turbofan engines could perhaps have further encounter deeper combustion instability, and even more critical, axial flow compressor instability, resulting in “engine surge” – an engine air flow reversal pre-induced by “rotating stall” – an engine thrust reducer, altogether leading to a rare catastrophic turbofan engine fire during airborne takeoff (see a brief detailed explanation for laypersons of these rare catastrophic turbofan engine instabilities in the Appendix section).
The pilots would then immediately have to shut off the left turbofan engine, and immediately attempt to land the Boeing 767 with the single right turbofan engine in functioning operation. This is how these massive jumbo commercial airliners are designed, manufactured, and tested to do fortunately.

Still, experts present another scenario of truths associated with the Boeing 767-200ER’s Pratt & Whitney JT9D-7R4D engine safety breach of an undetected fuel leak prior to takeoff.

The accident could have been catastrophic had the jet taken off with a fuel leak, Greg Feith, a former crash investigator for the National Transportation Safety Board, told Reuters.

“Once the aircraft is airborne, it becomes a flying blowtorch,” Feith said. “The fire intensifies and you don’t know what system or structure it’s going to burn through.”

Fire could damage a wing and fuselage, or cripple hydraulic and electronic control systems, Feith said, potentially making an emergency landing impossible. It could also ignite fuel tanks in the wings, especially if fuel vapor were present, he said.

PW jt9d cutaway high - Fuel Leak Causes Engine Fire on Boeing 767 Prior to Takeoff in Florida


How do aircraft engines achieve catastrophic mechanical failure and how can this be mitigated?

Air enters the Pratt & Whitney JT9D-7R4D turbofan engine through the fan section (indicated in the photo below) at a mass flow rate of about a ton of air per second.

Five parts of this massive volume of air passes bypasses over the engine core into an exit nozzle past the turbine section, producing a substantially large amount of exit thrust. Whereas, one part of the inlet fan volume of air passes into the engine core begin at the compressor section.

From here air then continues to flow into the combustor (where it is mixed with fuel for combustion).

Subsequently, those combusted, hot gases pass into the turbine section (which not only produces additional exit thrust force of the engine, but also the turbine section serves to turn the engine core shaft, which turns the compressor blades inside the compression section and also the fans blades inside the fan section, and thus, start all over again the dynamic loop of how an aircraft engine properly operates).

The rotor blades in the turbine get very hot at about 1,800 degrees Kelvin or even more, so it is necessary to cool the turbine blades based on limiting thermal restrictions on material science. The tangential on-board injector’s job is to channel cool air from the compressor section into passages between the turbine blades in the turbine section.

Here is a cut-away of an actual Pratt and Whitney JT9D-7R4D turbofan engine in a museum, marked it up to help us see where the main engine components of the fan, compressor (including the air-fuel combustion chamber), and turbine sections are (including the identified portion that landing on Church and Murray Street, below the World Trade Center fire on 9-11):

PW_jt9d_cutaway_high 2

The operating range of aircraft turbofan engine compression systems is limited by two classes of aerodynamic instabilities (Fig. 1) known as rotating stall and surge [1].

Rotating stall is a multidimensional instability in which regions of low or reversed mass flow (i.e., stall cells) propagate around the compressor annulus due to incidence variations on adjacent airfoils [2–5].

Surge is primarily a one- dimensional instability of the entire pumping system (compressor, ducts, combustion chamber, and turbine). It is characterized by axial pulsations in annulus-averaged mass flow, including periods of flow reversal through the machine.

In high-speed compressor hydrodynamics across compressible flow regimes [6], rotating stall is generally encountered first, which then (loosely) “triggers” surge (often after a few rotor revolutions [2]).

This work [13] proposes schemes to passively control compressible rotating stall of high-speed compressors.

Nonetheless, with either instability, the compression system experiences a substantial loss in performance and operability, which sometimes result in catastrophic mechanical failure.

An experience-based approach for avoiding such performance loss is to operate the compressor at a safe range from the point of instability onset (i.e., imposing a stall margin). The stall margin ensures that the engine can endure momentary off-design operation. The margin also reduces the available pressure rise and efficiency of the machine (see Fig. 2).

It is proposed here that incorporating tailored structures and aeromechanical feedback controllers, locally-sensed by unstable compressible perturbations in annulus pressure, and actuated by non-uniformities in the high- speed flow distribution around the annulus, can be shown to inhibit the inception of a certain class of modal (long wave) stall of high-speed compressor devices. As a result, the stable operating range will be effectively extended allowing higher compressible performance and operability.

The fundamental proposition here [13] is high-speed stall onset just does not happen—it is triggered by an interdependent compressibility chain of critical Reynolds (boundary layer) and Mach (kinetic-thermal energy transfer) events. The commencement of these interdependent Reynolds and Mach events can be passively controlled, once their proportional sensitivity are monitored, sensed, and mechanically mitigated adequately in balance of performance, operability, weight, and reliability integrated with more conventional schedule-type control to justify the risk of such passive approaches offered herein.

In theory, fundamentals of a number of sensor-actuator schemes for rotating stall control were originally proposed early-on in Hendricks and Gysling [7]. In practice, a passive stall control program [13] could potentially be integrated with conventional control schedules of adequate change of fuel valve position, bleed valves, and re-staggered stator programs developed appropriately for profitable usage on compression systems operating in a highly-sensed compressible flow environment.

PW_jt9d_cutaway_high 3

Fundamental References for Additional Readings in the Field of Aircraft Engine Propulsion Stability

  1. Emmons, H. W., Pearson, C. E., and Grant, H. P., 1955, ‘‘Compressor Surge and Stall Propagation,’’ Trans. ASME, 77, pp. 455–469.

  2. Greitzer, E. M., 1976, ‘‘Surge and Rotating Stall in Axial Flow Compressors, Part I & II,’’ ASME J. Eng. Power, 99, pp. 190–217.

  3. Greitzer, E. M., 1980, ‘‘Review: Axial Compressor Stall Phenomenon,’’ ASME J. Fluids Eng., 102, pp. 134–151.

  4. Greitzer, E. M., 1981, ‘‘The Stability of Pumping Systems, The 1980 Freeman Scholar Lecture,’’ ASME J. Fluids Eng., 103, pp. 193–242.

  1. Day, I. J., 1993, ‘‘Stall Inception in Axial Flow Compressors,’’ ASME J. Turbomach., 115, pp. 1–9.

  2. Gysling, D. L. et al., 1991, ‘‘Dynamic Control of Centrifugal Compressor Surge Using Tailored Structures,’’ ASME J. Turbomach., 113, pp. 710–722.

  1. Gysling, D. L., and Greitzer, E. M., 1995, ‘‘Dynamic Control of Rotating Stall in Axial Flow Compressors Using Aeromechanical Feedback,’’ ASME J. Turbomach., 117, pp. 307–319.

  2. Moore, F. K., 1984, ‘‘A Theory of Rotating Stall of Multistage Compressors—Parts I – II – III,’’ ASME J. Eng. Gas Turbines Power, 106, pp. 313–336.

  1. Moore, F. K., and Greitzer, E. M., 1986, ‘‘A Theory of Post Stall Transients in Axial Compression Systems: Part I—Development of Equations,’’ ASME J. Eng. Gas Turbines Power, 108, pp. 68–76.

  2. Greitzer, E. M., and Moore, F. K., 1986, ‘‘A Theory of Post-Stall Transients in Axial Compression Systems: Part II—Application,’’ ASME J. Eng. Gas Tur- bines Power, 108, pp. 231–239.

  3. Haynes, J. M., Hendricks, G. J., and Epstein, A. H., 1994, ‘‘Active Stabilization of Rotating Stall in a Three-Stage Axial Compressor,’’ ASME J. Turbomach., 116, pp. 226–239.

  1. Longley, J. P., 1994, ‘‘A Review of Non-Steady Flow Models for Compressor Stability,’’ ASME J. Turbomach., 116, pp. 202–215.

  2. McGee, O. G., and Coleman, K. L., 2013, “Aeromechanical Control of High-Speed Axial Compressor Stall and Engine Performance—Part I: Control- Theoretic Models,” ASME J. Fluids Eng., 135, March 2013. Coleman, K.L., and McGee, O.G., 2013, “Aeromechanical Control of High-Speed Axial Compressor Stall and Engine Performance—Part II: Assessments of Methodologies,” ASME J. Fluids Eng., 135, May 2013.

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