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NTSB Issued Final Report for the 2019 Acclaim Ultra down at DVT


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The final report on this accident was issued a couple of weeks ago after nearly 3 years.   Basically no new information was provided.  Continental reassembled the engine with some new parts that had been destroyed in the accident and it ran fine.

We'll never find out what really caused this accident, but the only reasonable guess, since they couldn't find anything wrong with the engine, would be vapor lock.  I was coming back from MooneyMax 2019 that day and landed in Chandler a few hours before the accident.  I remember the temperature at Chandler when I landed was 102°, a perfect setup for vapor lock.  I wish he had just circled down and landed at P48 even though it was a gravel strip.  The airport has since been closed.

Report_WPR19LA167_99594_5_30_2022 8_17_42 PM.pdf

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  • donkaye changed the title to NTSB Issued Final Report for the 2019 Acclaim Ultra down at DVT

Vapor lock in flight would be very unusual, I have never heard of it in a GA airplane, the reason it would be very unusual is the fuel is being used and often there is a return line as well, meaning there is constant cool fuel flowing through the lines. You usually see it after refueling on a hot day of course when you restart.

Car gas however is much more likely to vapor lock if you have an aircraft that is allowed to use it, often a continuous fuel pump may be added and or cooling ducts to parts of the fuel system etc.

For Certification the FAA requires a hot fuel test where the fuel is heated on the ground to a hot temp and then the aircraft is flown at max continuous power to its service ceiling, the purpose of the test is checking for vapor lock, the higher altitude of course due to reduced pressure reduces the temp the fuel will boil, This test came from problems WWII fighters experienced especially in the Pacific theater, Image a dark blue Corsair sitting in the sun soaking up all that heat, then flown at a phenomenal climb rate to the flight levels, they rarely experienced vapor lock, so we now test for it. Not sure which airframe I just said Corsair as they were dark blue I think.

If you ever get vapor lock you should see fluctuating fuel pressure and if you have the old style fuel flow meter that works off pressure, it will be bouncing around too, of course if you suspect vapor lock turn on the boost pump, if it’s vapor locking after the pump (most probable) that should eliminate the vapor lock.

https://www.law.cornell.edu/cfr/text/14/25.961

I’ve had to fly a few of these and ended up with a couple hundred gallons of free Avgas as the PT-6 is allowed to burn Avgas for a limited time, and you test the worst case fuel.

 

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I make a habit of reading these accident reports, not so that I can criticize the person's decisions, but so that I can learn lessons which I hope I will use If I'm in a similar situation. These reports are sobering and remind me of what a heavy responsibility that a pilot's license carries with it.

My take-away from this one is that if I am faced with something similar I will try to convince myself to take the closest landing option*, even though under normal circumstances it might not be the best option. I will try not to overthink it and go further toward an airport that might have better maintenance options etc. That can always be worked out later. It's been repeated many times on this site, but the airplane when it's in trouble, belongs to the insurance company. I'm going to try to remember not to do anything to save the airplane that would put myself or my passengers in greater danger. Since this airplane had less than 20 hours on it I understand the motivation to save it though. All of this is easy to conclude while drinking my morning coffee, but much harder to implement when it really counts.

 

*This is also a similar lesson take-away from the Tampa accident last November (trying to go to another more convenient airport)

 

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6 hours ago, donkaye said:

The final report on this accident was issued a couple of weeks ago after nearly 3 years.   Basically no new information was provided.  Continental reassembled the engine with some new parts that had been destroyed in the accident and it ran fine.

We'll never find out what really caused this accident, but the only reasonable guess, since they couldn't find anything wrong with the engine, would be vapor lock.  I was coming back from MooneyMax 2019 that day and landed in Chandler a few hours before the accident.  I remember the temperature at Chandler when I landed was 102°, a perfect setup for vapor lock.  I wish he had just circled down and landed at P48 even though it was a gravel strip.  The airport has since been closed.

Report_WPR19LA167_99594_5_30_2022 8_17_42 PM.pdf 97.37 kB · 12 downloads

with  2 of the three components replaced that allow an engine to run, it would be very difficult to point to anything as a cause of the engine shut down. While vapor lock cannot be eliminated from this causal list, anything to do with spark or fuel cannot either, as the certainty of mags and fuel pump were damaged beyond use from the fire and were replaced on the otherwise functioning block to run a test.
RIP Mark

 

MVIMG_20190423_155505.jpg

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2 hours ago, A64Pilot said:

Vapor lock in flight would be very unusual, I have never heard of it in a GA airplane, the reason it would be very unusual is the fuel is being used and often there is a return line as well, meaning there is constant cool fuel flowing through the lines. You usually see it after refueling on a hot day of course when you restart.

Car gas however is much more likely to vapor lock if you have an aircraft that is allowed to use it, often a continuous fuel pump may be added and or cooling ducts to parts of the fuel system etc.

For Certification the FAA requires a hot fuel test where the fuel is heated on the ground to a hot temp and then the aircraft is flown at max continuous power to its service ceiling, the purpose of the test is checking for vapor lock, the higher altitude of course due to reduced pressure reduces the temp the fuel will boil, This test came from problems WWII fighters experienced especially in the Pacific theater, Image a dark blue Corsair sitting in the sun soaking up all that heat, then flown at a phenomenal climb rate to the flight levels, they rarely experienced vapor lock, so we now test for it. Not sure which airframe I just said Corsair as they were dark blue I think.

If you ever get vapor lock you should see fluctuating fuel pressure and if you have the old style fuel flow meter that works off pressure, it will be bouncing around too, of course if you suspect vapor lock turn on the boost pump, if it’s vapor locking after the pump (most probable) that should eliminate the vapor lock

 

It's true, we'll never know, but the POH says to turn on the low boost above 12,000' for vapor suppression.  I don't know if that includes DA above 12,000', and we don't know if he turned on the low boost.  Also, we don't know from the report if there was total loss of power eventually.  This accident was disturbing to me for so many reasons I can't get into here.  Mark had taken me over to Minden the week before to pick up my plane after installation of the GFC 500.  I had been unable to do his transition training due to insurance problems.  He had completed his transition training with another Mooney instructor.  He was excited about the plane.

 

Screen Shot 2022-05-31 at 6.55.30 AM.png

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My take would be above 12K DA, because the airplane only “knows” DA. But if you turn it on early it’s not going to hurt anything. I know some of the Bonanza guys who will use boost on a hot day to keep cyl head temps lower, apparently some models don’t cool so well. I find it interesting that low boost is on if ITT approaches 1450, is that assuming your full rich already?

Never mind I reread it, it does say full rich already

Interestingly its the same altitude that your supposed to turn the boost pump on, on an OH-58 helicopter too. Back in the day the Army burned JP-4 which is gasoline based and much more likely to vapor lock, and all helicopters, turbines any way have normally a suction fuel system, which of course makes vapor lock more likely.

Depending on fuel level many helicopters will have to suck fuel up several feet.

Some turbine airplanes will put jet pumps in the tank so the whole system is pressurized, but helicopters don’t, or I should say Military ones don’t because I’m not familiar with every helicopter.

Was he above 12K? I know nothing about this accident

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21 minutes ago, A64Pilot said:

Was he above 12K? I know nothing about this accident

@A64Pilot The accident report link in Don's first post should answer most of your questions.

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I would guess mechanical fuel pump, we had a customer lose one 10 to 15 min after takeoff in their Cirrus, he elected to not use the chute and broke a wheel pant on landing in a peanut field. He said the boost wouldn’t keep it running, but I’ve always wondered.

Put the airplane on a roll on roll off wrecker, police escort to local airport, replaced pump and was on his way. 

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My recollection from looking at the flight path was that it appeared that he could have gone to P48 pretty easily, or if he'd initially headed straight to DVT could likely have made that, but for some reason he got steered towared Luke/Glendale and lost some altitude in that direction before turning back toward DVT.   I don't think he was familiar with the area, so perhaps he was offered Luke/Glendale and just took it without knowing there were closer alternatives.

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While one cannot say for sure if Mark did have the boost pump on after climbing thru 12K feet, I have heard from  3 people this topic was well covered in his training and at a dinner prior to him leaving his factory transition training, and we typically act/react how we are trained.

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IMHO Continental should provide a cooling blast tube from the aft baffle, directed at the mechanical fuel pump. The TSIO-550 used in the Acclaim, and a similar version in the Cirrus SR22T, both have an exhaust crossover that runs just under and aft of the fuel pump. Even though the crossover has a shroud around it, for the cabin heat, it still radiates plenty of heat in a very tight area. 

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42 minutes ago, A64Pilot said:

What that aircraft are tested for vapor lock with hot fuel, or that one won’t  run without a functioning fuel pump and I know of one that the pump quit?

Where’s the opinion?

A64Pilot, you said: "I would guess mechanical fuel pump". Most of your posts seem to be opinions rather than facts.

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1 hour ago, philiplane said:

IMHO Continental should provide a cooling blast tube from the aft baffle, directed at the mechanical fuel pump. The TSIO-550 used in the Acclaim, and a similar version in the Cirrus SR22T, both have an exhaust crossover that runs just under and aft of the fuel pump. Even though the crossover has a shroud around it, for the cabin heat, it still radiates plenty of heat in a very tight area. 

What if a boost pump fails while in use?  Could that not be potentially worse than not using it at all?  The hot fuel between the mechanical pump and the boost pump would go from whatever pressure the boost pump provides to ambient almost instantly.

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Are there any facts stated in this thread, other than there was a crash? Accident report didn’t state anything on altitude, even said one serious injury, but I guess it was fatal?

Vapor lock was postulated so I stated it’s tested for and supplied the link of how the test is conducted to try to show that vapor lock would be unusual, mags were postulated but as there are two of them that’s unlikely, fuel pump was also thrown out as a guess and I agreed, but it could have been anything.

So those were facts, but my agreeing on the fuel pump is the guess in the thread?

I didn’t imply he didn’t turn boost on as apparently he has friends here and that may not have been nice.

 While I have no idea which engine monitor he had if any, but many record data, if that had been available it may have answered questions.

Any of these accident threads are speculation, that means opinions

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11 minutes ago, A64Pilot said:

Are there any facts stated in this thread, other than there was a crash? Accident report didn’t state anything on altitude, even said one serious injury, but I guess it was fatal?

 

The accident report did state that the pilot succumbed to his injuries on page 3 under Factual Information section.

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31 minutes ago, Shadrach said:

What if a boost pump fails while in use?  Could that not be potentially worse than not using it at all?  The hot fuel between the mechanical pump and the boost pump would go from whatever pressure the boost pump provides to ambient almost instantly.

Yes it would drop almost instantly to the pressure it would have been prior to the boost pump being on, which in a low wing aircraft is usually slightly lower than ambient and on a high wing slightly higher.

But how would that be worse?

One way is to include two boost pumps, that’s what we did on the GE H-80, primarily so the pilot could turn the second one on and continue to work until a replacement became available. However in that aircraft no pump was actually required, the engine was allowed to be run for 100 hours with no boost pump, at which time the engine driven HP pump had to be replaced because the possibility of cavitation damage due to vapor lock existed. I had to do two hot fuel tests one with pump on one without.

If anyone is interested here is a link to an inflight engine failure investigation I participated in, I was the NTSB POC at the time. The MVP-50T had recorded ALL engine parameters at a data sample rate of 3 times per sec, GE was trying to blame the Weldon fuel pump, but the MVP showed it had positive pressure at all times to the engine. GE was having fuel control problems and wouldn’t own up for some reason.

http://www.kathrynsreport.com/2019/09/loss-of-engine-power-total-thrush-s2r.html

I am familiar with accident investigations as I was Military trained in them, and have attended several as the factory rep. This one was after I Retired but I was asked to attend, so I did.

Edited by A64Pilot
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15 minutes ago, A64Pilot said:

 While I have no idea which engine monitor he had if any, but many record data, if that had been available it may have answered questions.

 

He was flying a Mooney Acclaim Ultra.  Pretty sure it has an engine monitor.  Not sure if it survived the crash though.

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19 minutes ago, A64Pilot said:

 While I have no idea which engine monitor he had if any, but many record data, if that had been available it may have answered questions.

Actually, the airplane was equipped with the G1000 NXi.  I believe there is data recording with that unit, but I could be wrong.  Do you know, Mike?  Unless it was totally destroyed, you would  think the NTSB might have been able to get some engine data from it and found out the cause of the engine issue.

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5 minutes ago, Greg Ellis said:

The accident report did state that the pilot succumbed to his injuries on page 3 under Factual Information section.

Thank you, Lord 5 months later? That must have been bad, sorry to hear that.

The blank after page 2 threw me, until you pointed it out I hadn’t read it. However am I missing something still as it seemed he didn’t make it to 12,000?

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1 minute ago, A64Pilot said:

Thank you, Lord 5 months later? That must have been bad, sorry to hear that.

The blank after page 2 threw me, until you pointed it out I hadn’t read it. However am I missing something still as it seemed he didn’t make it to 12,000?

 

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1 hour ago, A64Pilot said:

Thank you, Lord 5 months later? That must have been bad, sorry to hear that.

The blank after page 2 threw me, until you pointed it out I hadn’t read it. However am I missing something still as it seemed he didn’t make it to 12,000?

That's why I mentioned DA.  I didn't do a DA check that day as I was descending, but Chandler at 2,243' had a temperature of 102°F that day.  Standard at SL is 59°.  Assuming the standard lapse rate of 3.5°F/1000', standard at Chandler was 51°.  The temperature was 51° over standard.  A rule of thumb is DA increases 1,000' for every 15°F over standard.  That means the DA increase from standard at Chandler was 51/15 x 1,000 = 3,400' and the DA was about 5,600'.  I'm going to extrapolate and say that at 9,100' the DA was over 12,000'.

Frankly, the POH says 12,000' and doesn't quantify to DA.  So. if you wait until 12,000 to turn on the boost, it could really be above 15,000' from a DA point of view.  It's either confusing or the writers of the POH deliberately didn't take DA into account.  I'm certainly open to hear why that might be.

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1 hour ago, donkaye said:

Actually, the airplane was equipped with the G1000 NXi.  I believe there is data recording with that unit, but I could be wrong.  Do you know, Mike?  Unless it was totally destroyed, you would  think the NTSB might have been able to get some engine data from it and found out the cause of the engine issue.

Yes Don, it will do data recording with an SD card installed in the mfd. I know the NTSB are all over data recording instrumentation in GA accidents with JPI and Garmin Data  and if anything survived, it would have been mentioned. I am surprised it was not mentioned that it was unrecoverable, actually. What we do know is something caused the engine to act up, and only 3 things it could be air, fuel or spark, and of those components, most likely 2 of the 3 systems were damaged beyond the ability to test integrity from the resultant fire. From speaking in person with the gent, Tom Hunnicut, who pulled Mark from the plane, Mark had the plane on the ground then pulled up to avoid hitting an innocent in a car then hit the poles and the plane then caught fire.

Edit: on reflection, all 3 could have been compromised. If the intake system failed, losing boosted air and thus causing extreme rich and flooding with the low boost on in addition to all the other speculations. I am sure non of this has escaped scrutiny of the NTSB, Continental, or Mooney.

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