AvWeb blog ref Ghost

[Coyote Chris]

http://www.avweb.com/blogs/insider/AVwebInsider_GallopingGhost_207267-1.html

Galloping Ghost: NTSB Nails It

By Paul Bertorelli

I took an hour and a half to attend Monday's NTSB hearing on the Reno Galloping Ghost accident. To say it was an eye opener is an understatement. It's not much of an exaggeration, in my estimation, to assert that before it even took off, Galloping Ghost was a crater looking for a grid reference. The NTSB found that it was flying at the very edge of its structural and performance envelope, if not well beyond it.

How could this have happened? Perhaps the easiest way to answer that is to suggest that it occurred because of an uncertain confluence of an owner and team willing to press the limits, a racing association with weak technical oversight and a regulatory agency—the FAA—that simply wasn't in the loop. The NTSB found that the aircraft was significantly modified, to include the removal of the belly scoop, the addition of a new canopy, structural mods to the fuselage and tail and a boil-off unit that's popular among Reno races as a supplemental cooling system.

These are hardly uncommon mods for this class of airplane, but the FAA had no records on any of this except the boiler. The owners hadn't reported the rest. Given that Reno racers are experimental, I'm not sure they're required to. Yet had they done so, opined the board, the agency would likely have demanded more flight trials to prove the mods. Would a structures guy have seen serious issues with the scoop removal just by inspecting it? Maybe. The NTSB said that much of the data it reviewed was unique to Galloping Ghost, even though other unlimited Reno racers are similarly modified.

Galloping Ghost was clearly built to win. It was flying faster than it ever had by at least 35 knots and the engine was delivering more power than was ever asked of it. It rounded its last turn at more than 400 knots, rolled sharply left, then pitched up violently into a 17-G uncommanded pull that the NTSB said no human could tolerate. Yet even before the moment the accident scenario began, there was strong evidence that the airplane was coming apart. Like most aviation events, Reno is widely filmed and the NTSB had an unusual amount of good imagery to investigate this accident. It did a superb job of analyzing it.

In lap two of the accident race, the imagery showed deformation in the aircraft's skin, indicative of overloading, and a visible crack or gap opened in the canopy. Wouldn't the latter have been evident to the pilot? The conclusion seems to be that it should have been. Why it wasn't is a mystery.

On the accident lap, the final failure mechanism was loose or fatigued screws holding the left trim tab in place. (The Mustang has a pair of trim tabs, for redundancy, but the right one on Galloping Ghost was fixed in place.) The investigation revealed that self-locking nuts were re-used on the left tab and old paint on the fasteners suggested they were last installed 26 years ago. The screws were incapable of being properly torqued.

In the final turn, something excited flutter in the loose tab. Was it wake turbulence from the proceeding airplane or sympathetic vibration with a structure that might have already been buzzing? We may never know. But we know the result. Flutter is as relentless and unforgiving a phenomenon as anything in aviation and it can destroy robust structures in mere seconds. In Galloping Ghost, the fluttering tab failed the trim actuator rod, rendering the trim useless. It didn't help that the P-51's elevator bob weights and balance had been significantly modified. Jimmy Leeward was doomed the instant the tab buzzed. It didn't actually depart the elevator until well into the uncommanded pitch up.

In my view, as surely as the technical explanation for this accident was a structural failure, the reason for it was a cultural failure. In her opening remarks, NTSB Chairman Deborah Hersman showed an acute understanding of why Reno pilots are willing to assume risk, but she also observed that exposing spectators to risk is quite another thing and an out-of-control airplane is a risk to everyone.

As pilots, we tend to dismiss the concerns of non-aviators as the paranoia of people who live uninspired lives in a cocoon, unwilling or unable reach out for the thrill that animates the rest of us. But there's a degree of cynicism in that dismissiveness and it can get people killed. In my view, the Galloping Ghost accident doesn't appear to be the result of willful ignorance, rather just plain ignorance. It also seems reasonable to assume, based on the NTSB's findings, that it could have been avoided if the owners had merely examined the risks critically and conducted more flight testing. As the NTSB suggested, the Reno Racing Air Racing Association needs better technical oversight of aircraft flying there and it has agreed to do that.

A word here about the NTSB, which a friend of mine once described as "government done right." I'm not easily wowed, but watching this hearing, I couldn't help but be impressed with the thoroughness and speed of the NTSB's probe into this accident. Moreover, the board members questioning of the investigators showed deep technical grasp of the issues. They asked what I'd ask. And then some. Deborah Hersman's queries and closing remarks were respectful and set just the right tone; firm, no-nonsense, but not overbearing. Positive changes have already come in the wake of this accident. Let's hope they stick.

A video of the full hearing will be available on the NTSB Web site in a few days. It's worth the time to watch. I'll add a link when it's available.

In the meantime, you can download the NTSB's statement of probable cause here (PDF).



Comments

[flyingjibus]

Re: AvWeb blog ref Ghost

Whomever wrote that obviously doesnt know much about air racing.

[AirRaceFan]

Re: AvWeb blog ref Ghost

And how did you come to this pearl of wisdom?

I am not the person who posted that comment, and I cannot speak for him/her. But I will throw my two cents in anyways.

I don't know how much the person (Paul) who wrote the blog post knows about air racing. But it certainly seems they don't get the "spirit" of what racing is all about.

It's not much of an exaggeration, in my estimation, to assert that before it even took off, Galloping Ghost was a crater looking for a grid reference. The NTSB found that it was flying at the very edge of its structural and performance envelope, if not well beyond it.

I find the comment that GG was a crater looking for a location to simply be unfair - a low blow. The NTSB, god bless 'em, is an organization that deals with very factual and dry content; they do tremendous work helping us to understand why transportation aircraft have had incidents or accidents. A comment that a given aircraft was at or beyond it's structural/performance envelope would be entirely relevant in the context of a theoretical incident or accident with a a 737 or A320 flown beyond it's known performance envelope. Thing is, we aren't talking about airliners here; we're talking about vintage military aircraft that are extensively modified for racing. Most of us aren't here to watch bone stock planes round the pylons with stock motors at rated military power at no more than 30* of bank angle. So of course the NTSB found that GG was not operating well within "ratings." That's the point of air racing; and it should not in any way be held against the racers.

The NTSB found that the aircraft was significantly modified, to include the removal of the belly scoop, the addition of a new canopy, structural mods to the fuselage and tail and a boil-off unit that's popular among Reno races as a supplemental cooling system.

Did anyone, for even a split second, think the NTSB would NOT find a "significantly modified" aircraft? Modifications are not implicit with guilt, intentional ill will, impropriety, or any other negatively connotated adjective when you are talking about racing. GG was a racing aircraft. We aren't talking about a 737 operated by a "speed freak" pilot who installed engines off a 757 with riveted on afterburners, and then attempted to jet 150 passengers around the country.

but the FAA had no records on any of this except the boiler. The owners hadn't reported the rest. Given that Reno racers are experimental, I'm not sure they're required to. Yet had they done so, opined the board, the agency would likely have demanded more flight trials to prove the mods.

S/he apparently doesn't know if it's required to report this stuff to the FAA, but acts / writes as if this is some kind of implicit association with guilt or negligence. Not fair! And this is where I start to agree that the author does not understand air racing: quite simply, you can't operate these aircraft at race power for extended periods of time for flight testing/trials. If the FAA mandated that every gold class racer put in 10 hours of time at race power/speeds in order to "prove" their mods, gold class would be finished. The motors don't last that long, the wear and tear on the race aircraft would be entirely prohibitive, just the cost of fuel/oil/chemicals to keep a competitive gold class racer at race power for 10 hours would be prohibitive even if the motors and equipment COULD last that long. The nature of race aircraft is that if you put it in the sky long enough at race power, something will fail. Then, (in this world of "more flight trials"), even more flight trials will be called for, more failures will be experienced, until someone stops and realizes "hey, this isn't a stock airplane anymore. We can no longer expect it to meet the requirements and standards set for the stock airplane." Otherwise, eventually the boil off system will fail and the "logical" conclusion is to put the scoop back on, the canopy will be found to limit visibility and the "logical" conclusion is to put the stock canopy back on, the motor will blow and the "logical" conclusion will be to reduce boost.... Suddenly, you're back to a stock plane.

We are not proving a 737 here.

In lap two of the accident race, the imagery showed deformation in the aircraft's skin, indicative of overloading, and a visible crack or gap opened in the canopy. Wouldn't the latter have been evident to the pilot? The conclusion seems to be that it should have been. Why it wasn't is a mystery.

Once again, this is racing. At least half the aircraft in the field have been photographed showing deformations/stresses in the skin. It is the nature of the beast. Thin sheet aluminum flexes when stressed. When pushed by pressure (whether air pressure, structural, whatever) into spars, ribs, longerons, etc.; or twisted by rotational forces, it will deform (whether by forming ripples, or exposing the general shape of the underlying structure, etc.). I am not an aeronautical engineer, but I know enough to know that in many cases, the skin/sheet aluminum is part of the strength of the structure, and IS exposed to strain/stress.

Is it indicative of a change in load? Absolutely! Is it indicative of OVERloading? Only analysis can tell you for sure, but I think a little thoughtfulness can go a long way here. These were fighting aircraft when used for military purposes, and a quick check will show you that the P51 was rated for beyond 5 "G" force; RARA calculates the unlimited course on a 2.5 "G" course profile. The same stresses in the skin were probably evident back in the 40's on stock P51's when they were exposed to the same kind of "G" loading; only they didn't have the super high resolution photography equipment to capture those details back then. Remember, these are aircraft, built to be light and to only withstand the maximum expected loading - they are not solid as bricks, they are hollow, flexible, .... Anyone who has ever watched the wing of a 737 in even light turbulence will know and understand that airplanes bend and flex. Flexing is part of flying. To the best of my knowledge, no air racer has ever suffered a significant sheetmetal/skin failure due to cracks/fatigue propagated by stressed skin. Cracks / stress / fatigue take time to propagate, and most of these aircraft (especially the fastest ones) are inspected and taken apart often enough (and get so little airtime) that any fatigue cracking will be caught long before it becomes an issue. Metal is ductile and has some "give"; if these aircraft were operated significantly overloaded, you would see them landing with PERMANENT deformations - like you see when an aircraft has been landed too hard and has overstressed the fuselage, for example. I'm also not saying that because nothing has ever happened that it should be ignored; but this phenomena is well enough known that it seems a little silly to cry wolf over it.

It didn't help that the P-51's elevator bob weights and balance had been significantly modified.

Another unfair comment - air racers are modified, and modification is not implicit with a desire to put GG into the ground. If a given modification was determined to cause a problem, then fine and fair - state that; but picking random modifications to frown at for the sake of having something to frown at is not productive.

In my view, as surely as the technical explanation for this accident was a structural failure, the reason for it was a cultural failure.

If this were an airline full of 737's or A320's, I would COMPLETELY agree - but it's not, it's air racing. Modifications, pushing the envelope, trying new ideas, etc. is not "bad culture" when you are participating an event where that is the whole point.

This is a long running battle that will run long beyond our generation. I'm sure the first time someone hopped in their model A, found a long straight flat section of dirt and floored it to see how fast they could go, there was someone else there shaking their head thinking how unsafe it was. For as long as mankind has had the wheel, there has been a certain subset who sought to make that wheel turn faster. That's not bad culture.

And therein lies why I agree that the original author of that blog post doesn't necessarily "get" air racing. Racing a car is inherently less safe than riding in a bus. Racing a boat is inherently less safe than cruising on a cruise ship. And racing an airplane is inherently less safe than flying a 737. Heck, racing on a horse is inherently less safe than walking.

If you impose a culture of safety on air racing, you will see speeds regulated so that no aircraft exceeds the manufacturers recommended to speed. No more 4360's will be in the Furys, because they haven't been flight tested and the airframe is not designed to handle the additional load. P51's will be brought back to stock boost because the motors were never designed for the boost they are ran at now. All the clipped wings will be DQ'd because their flight envelope isn't fully understood.

Now, with all that said, I am NOT trying to say that safety should be ignored - far from it. But you have to stop the blame train before it gets to the point that go-fast modifications are suddenly unsafe and bad culture.

[xmh53wrench]

Re: AvWeb blog ref Ghost

Thank you AirRaceFan.....

I have a circle on my garage wall that I have been saying nearly verbatim what you have just typed.....I say it there because there are very few that would understand it.

I have said as well...."Take Bonneville, Edwards AFB, and Cape Canavral, mix them up and you have Reno. There is only one way to race and win and that's find the limit, and then find a new one, because I guarantee you the guy next to you is doing the same thing. Sure more testing may have shown a potential problem, but who is going to confine a racer to its test parameters, and guarantee it won't exceed those parameters during the heat of battle on the race course? The shame of this deal is the possiblity of poor maintenance, and or a few bad modifications. But there is only one way to go faster, and that is to go faster...."

[AirRaceFan]

Re: AvWeb blog ref Ghost

With all that said, I will also say the following:

If we can set aside the "racing is bad" culture bias, then perhaps some real learning and improvements CAN come from this.

First, this is an excellent opportunity to educate EVERYONE who ever touches an unlimited class racer, to remind them of the importance of what they do, to pay attention and think about their actions. Was it a bad choice to re-use a lock nut? perhaps, and perhaps not - we will never know who did that work, and what the reasons were. Maybe at the time it was installed, it did in fact torque correctly. If, the next time some mechanic somewhere installs a trim tab on a P51, and he or she stares at the hardware and thinks "you know, this stuff is probably good enough but this is a critical piece of the airframe and I think we really should put a new bolt and nut here", then air racing has become safer.

Second, if we can move past the "removing the scoop and installing a boil off system is bad" mentality, then we can get to the real questions that matter - have we weakened any critical structures, and if so, what do we need to reinforce/brace?

Third, the NTSB report does indicate that these fasteners were re-tightened more than once on GG, possibly several times in the past few years alone. I am not proposing that race teams hire dozens of statisticians and bean counters to analyze everything to incredible levels of detail, but a little review could go a long way. If you have a maintenance item that has cropped up numerous times, that could have catastrophic consequences if not corrected, AND there is no known explanation as to why the item keeps coming up, then a little extra research is warranted. I do realize that race planes change hands, that there are discontinuities in the knowledge/history of each plane, etc.; so this system will never be perfect. But if you can move past the "you are flying the plane too fast outside of it's limits" accusation, then you can get to the real question: why is this darn trim tab loose again?!?! Thus this event serves as a reminder of the importance of being vigilant. Little things do matter.

Fourth, the report indicates GG was being operated at a speed 40mph higher than ever before. I don't know if this is necessarily true, but I do not think that we should look down on a racer for trying to go fast!! With that said - it is common in many racing circles that the race vehicle must be proven at lower speeds prior to being permitted to operate at higher speeds. No, I'm not talking about exhaustive flight testing for years on end, etc.; but maybe it wouldn't be so bad if RARA imposed (for example) a 430mph limit on any "unproven" airframe for a minimum of 5 race course laps, followed by a landing/review of data; then a 450mph limit followed by the same review, increasing in 20mph steps until the ultimate race speed is achieved. That MAY have allowed enough margin to detect that a trim tab was fluttering prior to hitting the ultimate point of failure. If canopy deformation really was an issue, it MAY have permitted a correction to the issue before the point of deformation was significantly exceeded.

I don't feel that using such a system would be an undue burden - it would only take two practice runs around the pylons to get cleared to 470mph, which is already good enough to get into the Gold on Sunday; and a single heat race would have you cleared to 490mph. A completely unproven aircraft could still easily get into the Gold on Sunday if it proves worthy; the only "change" would be that the racer got to that speed through a few smaller "proving steps", and not one massive leap.

No system is perfect, no system will be 100% successful. But if we can move past the knee-jerk reaction that these planes are being operated in a bad culture, then we can see safety improve without harming the very thing we go to the races for.

[flyingjibus]

Re: AvWeb blog ref Ghost

And how did you come to this pearl of wisdom?

See the post below yours. Air race fan nailed it.

[al baby]

Re: AvWeb blog ref Ghost

What you are not seeing is the underlying message from the NTSB is, "we know air racing is risky, but what Jimmy did was egregious and unconscionable".

[Big_Jim]

Re: AvWeb blog ref Ghost

You people on here all need to be able to separate any personal feelings or connections that you have with the facts of the report.

Just because Jimmy was a friendly, likeable guy who had a super long tenure in the sport, does not mean that he was infallable. And I say this having been a friend of his and the family for a long time.

People make mistakes. When they do, the rest of us need to understand that they are only human. The report does not say that what he did was done so with bad intentions...it just says that mistakes were made, and the mistakes were made because of loopholes and deficiencies that--up until this point--were never enforced because they were never needed.

That has all changed now.

As with any accident, regardless of how much you/we want to defend this sport that we love so much...this is a learning opportunity. It's not throwing him under the bus, as so many of you want to see it as.

Hacker and I have discussed this over and over again on this and other racing forums whenver there is an accident like this. If this were in the military, it would be scrutinized to the n'th degree and blame squarely placed on where the issues were found--so that everyone would learn from it and steps would be taken so that it wouldn't happen again. In cases like that the pilot--if still alive--has to step up and take responsibility of saying 'yes, I messed up...and this is how'.

If this example prevents future incidents, then it has done its job.

Those of you criticizing the NTSB in this case have obvioulsy never participated in an investigation, have knowledge of how it works, understand why it is done, and have a clue as to what the writer was talking about. In the big picture, both the NTSB and the writer were spot on.

How we--fans, owners, administration--accept, react, and change the way we do business is what is going to dictate whether the sport recovers and moves on from this.

[AirRaceFan]

Re: AvWeb blog ref Ghost

What you are not seeing is the underlying message from the NTSB is, "we know air racing is risky, but what Jimmy did was egregious and unconscionable".

And that's where I disagree.

Replacing critical metal bolts with plastic bolts for weight savings would be egregious and unconscionable. Flying directly at the stands at race speeds, pulling up at the last second to "give the fans a show" would be egregious and unconscionable. Going up in an airplane that you had specific doubts would bring you back home (i.e. "on a wing and a prayer") would be egregious and unconscionable.

I guarantee you Jimmy thought GG was safe and would bring him back to the tarmac, to the same level of certainty that any air racer can have about a Gold class machine.

Frankly, I think the NTSB did a pretty compelling job, for the most part; I don't think they had any intention of saying or implying that this was an egregious or unconscionable accident. I think the blog author poured that sentiment into the pot himself because of his personal biases against Gold-class style air racing.

[xmh53wrench]

Re: AvWeb blog ref Ghost

I have a feeling my time here may have run its course...I may not be "of air racing", but I am "of RACING". I have to wonder what reactions would be if we were to substitute "Strega" or "Rare Bear" in all of these conversations.....but then this sort of thing could never happen in those camps.....I TRULY HOPE IT NEVER DOES!!!!!

....BAN AWAY, maybe I will just never "get it", the same as I believe some will never understand.

[AirRaceFan]

Re: AvWeb blog ref Ghost

Big Jim - 100% agree with you. We need to learn and improve from this event, which seems to be happening. Mistakes were made, yep. But we learn and grow from that, and (fingers crossed) will NEVER lose another p51 or pilot due to trim tab issues, ever again.

Accusing Jimmy of being egregiously unsafe or willfully careless serves no purpose, and chastising air racing for the modifications made to these race aircraft also serves no purpose. This kind of commentary, to me, is NO different than Rogers (of Mr. Rogers Neighborhood fame) going to a drag strip and shaking his head because "these tires have no tread, they must be unsafe!" when pointing out the Goodyear slicks.

Analyzing the mistakes and improving will save aircraft and lives - THAT serves a purpose.

[al baby]

Re: AvWeb blog ref Ghost

My point is the writer of the article points out facts from the NTSB documents and half of the posters on this site say he made it up, knows nothing and he must hate air racing. All of his comments were based on something that was said in the press conference on Monday. You can deny things all you want, Jimmy did some questionable things.

And as BigJim says, we should learn from this. I agree. But, first we must acknowledge that mistakes were made. Air them out in the open and stop trying to dust them under the rug. The only way we learn is if we look at the facts, without emotion. That's what the NTSB did and I believe the author of that article did also. I saw nothing stated that showed "his personal biases against Gold-class style air racing". What did I miss?

[AirRaceFan]

Re: AvWeb blog ref Ghost

I have a feeling my time here may have run its course...I may not be "of air racing", but I am "of RACING". I have to wonder what reactions would be if we were to substitute "Strega" or "Rare Bear" in all of these conversations.....but then this sort of thing could never happen in those camps.....I TRULY HOPE IT NEVER DOES!!!!!

....BAN AWAY, maybe I will just never "get it", the same as I believe some will never understand.

When it comes down to it, I don't think it matters whether it was GG or Bear or Strega involved with this incident. A highly modified aircraft went into the stands - period. The NTSB would have had nearly identical findings from any of the other top-tier Gold contenders - every aircraft is highly modified and unique in it's own way, they all have decades of history, they all probably have some less than perfect things going on. This sort of thing could have happened to any team.

People who want to point the finger at GG or Jimmy specifically, I assume must have some bias against that plane or person - or just aren't familiar with air racing, and are assuming that GG was the only "modified" racer being flown at Reno. I've personally watched Bear and others flirt with disaster - it's part of racing......

[AirRaceFan]

Re: AvWeb blog ref Ghost

My point is the writer of the article points out facts from the NTSB documents and half of the posters on this site say he made it up, knows nothing and he must hate air racing. All of his comments were based on something that was said in the press conference on Monday. You can deny things all you want, Jimmy did some questionable things.

And as BigJim says, we should learn from this. I agree. But, first we must acknowledge that mistakes were made. Air them out in the open and stop trying to dust them under the rug. The only way we learn is if we look at the facts, without emotion. That's what the NTSB did and I believe the author of that article did also. I saw nothing stated that showed "his personal biases against Gold-class style air racing". What did I miss?

I completely agree with the "look at facts without emotion" part. If a part was installed on GG that was demonstrably unsafe, then make that knowledge public so that other teams won't make the same mistakes. Learn everything that can be learned from the accident.

As for what you missed - I DO think that the writer of the article did in fact inject emotion and opinion and bias. He seems to have a problem with boil-off systems, airframe modifications, and the general fact that air racers are modified to go fast. The manner in which the author writes implies a strong distaste for go-fast modifications, in my opinion.

[al baby]

Re: AvWeb blog ref Ghost

When it comes down to it, I don't think it matters whether it was GG or Bear or Strega involved with this incident. A highly modified aircraft went into the stands - period. The NTSB would have had nearly identical findings from any of the other top-tier Gold contenders - every aircraft is highly modified and unique in it's own way, they all have decades of history, they all probably have some less than perfect things going on. This sort of thing could have happened to any team.

Can you share with me the DECADES OF HISTORY the Galloping Ghost has? If you read the material in the NTSB Docket, it is clear this is not the airframe which raced at Cleveland. It did not have decades of incident free laps around the pylons, especially in the final configuration.

People who want to point the finger at GG or Jimmy specifically, I assume must have some bias against that plane or person - or just aren't familiar with air racing, and are assuming that GG was the only "modified" racer being flown at Reno. I've personally watched Bear and others flirt with disaster - it's part of racing......

You are delusional. no one is pointing the finger at anyone without fact based documentation provided by the NTSB. You are the one with the bias.