WTF??

http://www.defensenews.com/art...-by-strong-tailwinds

F-35A engine fire at US Air Force base sparked by strong tailwinds

By: Valerie Insinna, July 12, 2017

WASHINGTON — U.S. Air Force investigators have found that last September’s F-35A mishap at Mountain Home Air Force Base, Idaho, was indeed an uncontained engine fire — albeit one started because of tailwinds present during engine start, not deficiencies with the aircraft’s Pratt and Whitney F135 engine.

According to a U.S. Air Force accident investigation board, or AIB, report signed May 9 by the board’s president and obtained by Defense News, the engine fire started after tailwinds forced hot air into the inlet of the jet’s integrated power pack. A chain of factors, such as insufficient torque and slow engine rotation speed, caused the F-35 to continuously supply fuel to its engine at an increased rate.

“During this mishap, however, the fire became uncontained due to the increased amount of fuel added while the engine rotation speed was slowing,” the report stated. “Once the uncontained fire started coming out of the aircraft exhaust, the tailwind carried it rapidly along the exterior surfaces of the jet.”

The pilot escaped from the aircraft but sustained burns to his head, neck and face.

The service is still evaluating how much it will cost to repair the F-35A involved in the mishap, which was assigned to the 61st Fighter Squadron at Luke Air Force Base, Arizona, and involved in a training flight at Mountain Home when the fire occurred. However, damage to the plane is estimated to amount to at least $17 million.

Ultimately, the mishap had little effect on F-35 training and operations. After the fire broke out on Sept. 23, the U.S. Air Force announced that it had no plans of grounding its F-35As — a sign that the service believed the incident arose because of weather or human factors rather than a design flaw. The F-35 joint program executive office has not announced modifications to the jet as a result of the event.

The AIB report noted that aircraft systems, including the F135 engine, performed as designed. Still, investigators stated that more could have been done to prevent the mishap, especially in the realm of educating pilots.

For instance, the service did not include information about how tailwinds contribute to integrated power pack failures on its engine start checklist. Pilots were also not given any additional training on concerns related to tailwinds and were not aware of warning signs that the F-35 exhibits when tailwinds cause issues with the jet’s power and propulsion systems.

“[Integrated power pack] and engine start issues with a tailwind were known prior to the incident. However, the publications were written and communicated in such a way that the F-35A pilot community had only vague awareness of the issue. This vague awareness led to inadequate training for engine starts with a tailwind,” Col. Dale Hetke, the AIB’s president, wrote in his statement of opinion on the investigation.

The F-35 is renowned for its complex software and sensor fusion capabilities, but Hetke noted that the level of automation present in the aircraft led to some complacency within the pilot community.

“The F-35A engine start process is heavily automated, which drove a perception among pilots [that] the aircraft handled virtually all of the starting procedures, and so long as the dials were ‘green’ there was no problems,” the AIB report stated.

During the incident, the fire spread along about two-thirds of the aircraft’s aft surfaces, with most burn damage occurring on the top, side and underneath portion in the center of the jet, the report said.

Because the aircraft’s weapon bay doors are open during engine start, the fire spread to aircraft surfaces, panels, cables and components. The aircraft’s landing gear was damaged, and its integrated power pack will need to be replaced.

Investigators noted that the engine’s exhaust nozzle section was engulfed in flames but did not spell out how much of the engine will need to be repaired or replaced.

quote:

damage to the plane is estimated to amount to at least $17 million.

That's absolutely insane. And frankly retarded.

I'm dumbfounded by the cost of these things.

So, if the aircraft is sitting with a wind coming from behind, it might catch fire trying to start the engine. Is that correct?

Somebody tell me again about this marvelous piece of design engineering, and how it replaces all other combat aircraft.

Why do I picture the Coyote in the cockpit and “Acme jet engines” painted on the side of the plane?

quote:

Originally posted by Elk Hunter:
So, if the aircraft is sitting with a wind coming from behind, it might catch fire trying to start the engine. Is that correct?

Somebody tell me again about this marvelous piece of design engineering, and how it replaces all other combat aircraft.

Apparently, smoke is being blown up the taxpayers' ass in more ways than one.

So how much tail wind is required for engine startup to be dangerous? While I'm untrained in such things, I'd think it would have to be pretty significant, that is, noticeably so. The way this is written I can't tell if we're talking 5 MPH or 50 MPH tail wind.

Don't start the new jet with it's butt pointed into the wind, got it.

... wait WHAT??!!?!?!?

quote:

Originally posted by jbcummings:
So how much tail wind is required for engine startup to be dangerous? While I'm untrained in such things, I'd think it would have to be pretty significant, that is, noticeably so. The way this is written I can't tell if we're talking 5 MPH or 50 MPH tail wind.

It sounds like the F-35 pilot didn't know either.

I can't recall any limits for the F-14/F-18, but I don't recall starting / taking off in any really wind days (outside of the ship steaming into the wind).

New technology, new issues. Pretty standard with new aircraft for things to be discovered. I don't deny the -35 program is over budget but all indications I have are that it'll do what it's supposed to.

This shits chess, not checkers.

A similar type thing (design and want, that failed to fulfil) with the F-15 "Limited Duty Mode".

F-15 has two engines, and three hydralic systems.

The engines are started using a JFS (Jet Fuel Starer) a small jet engine that turns a Central Gearbox(CGB) mounted to the front of the JFS, and this CGB drives one Airframe Mounted Accessory Drive mounted to each engine near the front with PTO shafts that engage from the CGB during engine start. These AMADs are where the hydralic pumps and generators are mounted.

PC1, PC2 (Primary Control) and Utility hydralic systems, 1 pump for each PC and two pumps for Utility. All of the hydraulics are run from various "splits" of all three systems for reduncancy and for "push/pull" (pressure on both sides of some actuators).

Since a great deal of maintenance required electrical and hydralic power, the designers thought it good to let the JFS/CGB/AMAD be used to supply limited duty hydralic and electrical power for some maintenance, testing and trouble shooting rather than requiring AGE (Aerospace Ground Equiment) typically a -60 (Jet engine powered generator that provides 115 three phase, 400 cycles electrical, and low pressure/high volume air) and a Mule (Hydralic test stand for three systems) and a C-10 Air conditioning cart, that uses the air pressure from the -60 to cool the avionics and such.

But, there were serious issues with overheats, fires and excessive wear on the JFS/CGB/AMAD componets, so it was pretty much restricted for use.

And many times simply doing an engine run would suffice, but some tasks could not be done during runs, and AGE was used.

The up side was that it did not cost much in the way of dollars to ot have the "luxury" of the LDM, maybe a bit more $ on AGE.

But that is just one of the very many things we learned to adapt to and overcome. Like many things, the brochure and the salesman's promises seldom survive the first payment, but you want to move forward, it is going to be the expectation that you won't get all you thought.

The F-35 is most remarkable and not the boondoggle many make it out to be.

How much do many spend on firearms, preparedness and whatnot? Yet we choose to be better armed and equiped than the threats we may never encounter.

I forgo a lot of things to have the best, and do not regret it after. Same as with the defense of the nation.

/broadbrush

It is not uncommon for strong tailwinds to cause engine startup problems with jets.

There are limits for most all jets on how much of a tailwind you are allowed to have. I don't remember what the limits are...it's been 15 years since my last engine run school in the AF.

I can remember the older Learjets had similar restrictions. I have pushed more than one around to get the ass end out of the wind.

RMD

I always spun the Rhino up as far as the apu would go when sitting tail into the wind because it would over temp easy in that scenario. Sounds like homeboy didn't get that gouge.

quote:

Originally posted by Elk Hunter:
So, if the aircraft is sitting with a wind coming from behind, it might catch fire trying to start the engine. Is that correct?

Somebody tell me again about this marvelous piece of design engineering, and how it replaces all other combat aircraft.

Yes, that is correct. Just like any other jet-powered aircraft, including airliners. No pilot with any sense attempts to start a jet with significant wind up the tailpipe. And Mountain Home AFB gets pretty windy at times. I once spent 15 minutes on a 10 mile final approach in a T-34C at Mountain Home.

quote:

“[Integrated power pack] and engine start issues with a tailwind were known prior to the incident. However, the publications were written and communicated in such a way that the F-35A pilot community had only vague awareness of the issue. This vague awareness led to inadequate training for engine starts with a tailwind,” Col. Dale Hetke, the AIB’s president, wrote in his statement of opinion on the investigation.

This is not the most disingenuous bit of bovine excrement I've ever read, but it's very close. Look us in the eye, Colonel, and tell us the best and brightest of the USAF hand-selected to fly the F-35 didn't know they shouldn't start a jet with a significant tail wind.

quote:

“The F-35A engine start process is heavily automated, which drove a perception among pilots [that] the aircraft handled virtually all of the starting procedures, and so long as the dials were ‘green’ there was no problems,” the AIB report stated.

Ah, sounds like pilot error, or at least over-confidence? I've read about this kind of thing before; pilots thinking the aircraft is so good that they got complacent (this is how they crashed the Boeing Model 299; the prototype for the B-17 - the test pilots were so confident in the aircraft's abilities that they missed a minor detail and destroyed the aircraft).


****Photos Deleted****

I love this forum; I know more about aircraft than the average dude on the street, but I never knew starting an jet engine with a heavy tail wind was ever a problem. Thanks to all the knowledgeable folks for educating us.

This message has been edited. Last edited by: Hound Dog,

^^^

That jet caught fire on takeoff at Eglin in 2015.

The King hanger (Hanger 130) is that big building in the background.

It is not the one that caught fire at Mt Home.

quote:

Originally posted by sigmonkey:
^^^

That jet caught fire on takeoff at Eglin in 2015.

The King hanger (Hanger 130) is that big building in the background.

It is not the one that caught fire at Mt Home.

Ah. My Google-fu is weak today. . .

quote:

Originally posted by sigmonkey:

But that is just one of the very many things we learned to adapt to and overcome.

Speak for yourself. As an E-3 dragging around a -60 cord just to do power-on checks every night on swings, fuck whoever thought the F-15 didn't need a battery, especially when you had a bay 5 on the C model that is bigger than the trunk in a 67 Cadillac DeVille. Also, fuck whoever designed that overly complicated secondary power setup you described and that I became intimately familiar with over the course of 4 years I maintained those pieces of crap. Every time the pilot gave me the JFS handle pull sign I said a small prayer that the thing would actually start. I've changed pumps & 50% switches on red balls several times because of that design. I spent almost a week changing out the utility reservoir due to several complications as well as accessibility being nearly non-existent. And don't even get me started on the canopy setup. I could rant all day!

From a mx perspective, the F-15 is a nightmare. I feel bad for those poor guard units that are still flying them at considerable risk to the lives of the pilots I might add. Thank God for A-10s, I wouldn't go back to crewing 15s for a six figure sign on bonus.

I have only heard a few things about the F-35 from a mx perspective, none of which have been good. Some things they don't want getting out to the public, but let's just say the "less with more" concept will come back to bite them in the ass with this jet. The new junk will require just as many maintainers as the old junk, no matter what Big Blue is putting out there.

^^^^^^
But remember the F15 and F14 were built in the same era, where you needed ground power and a huffer to start up.

Why? I have no fucking idea. I loved getting into the Super Hornet. Battery, APU, crank the left, start this mofo.

I just think it's funny that the F35 start is so "automated", like its fucking rocket science in the F18 or something. It's like 5 easy steps I have taught children under the age of 10 to accomplish in under 2 minutes of instruction.

quote:

Originally posted by RHINOWSO:
^^^^^^
But remember the F15 and F14 were built in the same era, where you needed ground power and a huffer to start up.

Why? I have no fucking idea. I loved getting into the Super Hornet. Battery, APU, crank the left, start this mofo.

I just think it's funny that the F35 start is so "automated", like its fucking rocket science in the F18 or something. It's like 5 easy steps I have taught children under the age of 10 to accomplish in under 2 minutes of instruction.

That's like starting a 737. So incredibly easy.

On the F-35 it's like the foot tailgate feature on the new SUVs. You just swipe your foot under the left rudder pedal and it fires right up.

quote:

Originally posted by RHINOWSO:
^^^^^^
But remember the F15 and F14 were built in the same era, where you needed ground power and a huffer to start up...

I loaded munitions on A-10s in the ANG 30+ years ago, we used the APU to run electrical checks and then the pilot used it to start the engines (GE TF34s). In Syracuse NY (and multiple TDY sites in CONUS) I do not remember any issues with tailwinds.