Mooney down in Petaluma CA 4/6/18 - Accident Report

[kortopates]

Recall this thread back from April 2018, when IFR pilot took off from Petaluma, CA in IFR conditions and came down a mile from the airport.

We now have the NTSB factual report out here https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20180407X35303&AKey=1&RType=Final&IType=FA 

Although the pilot made some mistakes, including telling ATC he was going to depart RWY 29, but was holding at RWY 11 and then departed RWY 11 after getting his release and void time. Pilot didn't fly the ODP and instead climbed to about 300' before turning left and climbing into the fog (per witness). But apparently what brought the plane down was water in the fuel, not CFIT and the plane came down at a very steep angle burying the engine in 3' of mud. Investigators found approx a 50-50 mixture of water and fuel in the fuel divider. They also provided a picture of the left fuel cap showing cracking in the outer o-ring. No mention was made of the inner o-rings but did mention the right cap was thermally damaged (post crash fire). 

More about the water from the report:

"Another witness reported that the accident airplane landed at O69 around 1645 the day before the accident and taxied to the fuel island. He stated that he helped the pilot obtain fuel, observed him sump the airplane's fuel tanks after refueling, and instructed him where to park for the evening. He stated that the accident pilot queried a FedEx pilot on the appropriate instrument departure procedure for runway 29...."

So we know the pilot was observed sumping the tanks after refueling the day before departure,  but we don't really know if he sumped the tanks again before departure after the plane had been out in the rain. But if he had, he probably would have found the water in the fuel since it brought the plane down very quickly after departure. However, the NTSB doesn't assign a cause to the accident - its only a "Factual" report.

There is no greater risk of water in the fuel than after our plane has been sitting on the ramp in the rain.  

Edited July 7, 2020 by kortopates

[MooneyMitch]

So very, very sad.   Such heartache for family left behind.

A strong lesson for us. 

[carusoam]

Something for @OSUAV8TER to take in... OSU knows fuel caps...

Water spread across the bottom of the tank will have a tendency to pool up near the fuel pick-up line when the nose is raised....

Be sure to sump the tanks.

Experience from the past... enough rain gets in the tank and the fuel sample cup is full with only one color... if you are unsure if that is clear or light blue... spit in it. Looking to see the spit sink. 

-a-

[Hank]

28 minutes ago, carusoam said:

Something for @OSUAV8TER to take in... OSU knows fuel caps...

Water spread across the bottom of the tank will have a tendency to pool up near the fuel pick-up line when the nose is raised....

Be sure to sump the tanks.

Experience from the past... enough rain gets in the tank and the fuel sample cup is full with only one color... if you are unsure if that is clear or light blue... spit in it. Looking to see the spit sink. 

-a-

I hold my fuel cup against a white section of my cowl and look for blue in the cup, then smell it for that particular gasoline fume aroma. Any that gets in my fingers should evaporate very quickly. 

[Matt Ward]

For what it’s worth, Sparky Immerson talks about proper fuel sumping technique in his book. This was something I never knew but have adopted. 

[carusoam]

Best to hold the sampler vertically for this, Matt...

-a-

[Jerry 5TJ]

If it was water in the fuel that got him, it likely “saved” him from CFIT.   The report says loss of control of as the main factor.   

You don’t want to turn left departing o69 Runway 11 in IMC. Which is just what he did. 
 

My hunch after reading the final report is he thought he was flying the departure for 29 which calls for a climbing left turn. However, he actually had departed 11.  

[Jeph357]

Water in fuel from a cessna

[jaylw314]

1 hour ago, carusoam said:

Nitpicking alert--that whole counterclockwise rotation in the northern hemisphere thing is bupkis.  Local effects and fluid motion play a much larger role than any Coriolis effect on anything that small a scale.  I also think you only get draining vortices when you you're draining something at a high rate in comparison to the tank depth.  Even when I had a drain stuck open, it still took a minute to drain out just a gallon (it did a good job cleaning out the drain, though).

[V1VRV2]

Terrible! I use a GATS jar.

[Fry]

I wonder why the fuel line of small aircraft take the fuel from the lowest point in the tank. That way, they are actually "preferring water", i.e. suck in any water first before taking fuel.

Wouldn't it be relatively simple to attach a flexible tube leading from the fuel line to a floating device inside the fuel tank? That floating device would float on water but not on fuel, such that if water is there, the fuel is taken from a point above the water.

(If you patent that now, it would be nice to mention me in the inventor list :-) )

[ArtVandelay]

I wonder why the fuel line of small aircraft take the fuel from the lowest point in the tank. That way, they are actually "preferring water", i.e. suck in any water first before taking fuel.
Wouldn't it be relatively simple to attach a flexible tube leading from the fuel line to a floating device inside the fuel tank? That floating device would float on water but not on fuel, such that if water is there, the fuel is taken from a point above the water.
(If you patent that now, it would be nice to mention me in the inventor list :-) )

You would be treating the symptom, not the disease.
If expecting substantial rain, I use painters tape over the fuel caps to insure no water gets in. Ounce of prevention is worth a pound of cure.

[Fry]

@ArtVandelay You would be treating the symptom, not the disease.

You are right with the "symptoms vs disease" of the airplane. But for the people on board, their "symptom" is death, and treating that is well worth thinking...

in any case, adding a device that will prefer fuel over water for the engine is IMO better than the "Cessna solution" of adding 10+ drainage points per wing.

[mike_elliott]

The fuel pickups are not directly on the floor of the tank, thats why the "unusable" fuel. The fuel drain valve opening is. it will drain the water out prior to showing fuel when sumping. Even this simple concept still doesnt prevent accidents such as this. 

[ArtVandelay]

[mention=11849]ArtVandelay[/mention] You would be treating the symptom, not the disease.
You are right with the "symptoms vs disease" of the airplane. But for the people on board, their "symptom" is death, and treating that is well worth thinking...
in any case, adding a device that will prefer fuel over water for the engine is IMO better than the "Cessna solution" of adding 10+ drainage points per wing.

The gascolator already separates water from fuel, as mentioned we already have a way to drain fuel from the fuel tanks.
So there are 3 ways to stop this
1. Prevent water entering the tank by either proper service and/or tape off the fuel caps.
2. Drain the water from the tanks.
3. Drain the water from the gascolator.

Cessna doesn’t have the pronounce dihedral that Mooney has. I don’t think we need 4th way, especially an untested new method. I’ll let someone else beta test it.

[kortopates]

17 hours ago, Jerry 5TJ said:

If it was water in the fuel that got him, it likely “saved” him from CFIT.   The report says loss of control of as the main factor.   

You don’t want to turn left departing o69 Runway 11 in IMC. Which is just what he did. 
 

My hunch after reading the final report is he thought he was flying the departure for 29 which calls for a climbing left turn. However, he actually had departed 11.  

Agreed, as I am sure your aware there is a 2200' peak just 4 nm to the north. But the plane only got 1 nm to the north before it literally fell out of the sky where the terrain was only ~300''. There was an eye witness that actually corrected the pilot on the radio when he announced he was holding at RWY 29 for IFR release, saying it was RWY 11 and the pilot acknowledged that:

 "Petaluma traffic, Mooney departing Runway 29"; the witness then transmitted "Runway 11" to which the pilot replied, "Thank you. I appreciate the help." He observed the airplane depart runway 11 and climb to an altitude about 300 ft above ground level before initiating a shallow left turn and disappearing into the fog.

Unfortunately, the witness's radio transmission didn't stop the pilot from changing his plan and then knowingly depart from RWY 11 apparently without knowledge of the ODP. Following the ODP for RWY 11 would have been easier for his IMC departure as well.

But the pilot didn't follow either ODP.  Both ODPs called for climbing to 1500' before making any turns. If the pilot truly turned left at only 300' AGL that too was contrary to the standard IFR departure with no turns till 400' agl off the departure end - as everyone is aware. But we probably can't assume the eye witness was that accurate about his estimate of 300' AGL and give him the benefit of the doubt on that one. But departing into low IMC or at night without following the ODP is a deadly mistake in the mountainous terrain of the west we see sadly repeated over and over again out here. 

Edited July 8, 2020 by kortopates

[OSUAV8TER]

These flush mounted fuel caps are more susceptible to letting water leak in and they have to be maintained in order to help prevent that. That is why Cessna went to a fuel cap that sits over the tank and is not flush mounted. Same with some Piper aircraft. It is much less risky. If you maintain the fuel cap then the risk is less. Even with the fluorosilicone o-rings, you still need to sump your fuel tanks. The hardware in these old fuel caps can wear down and even new o-rings won't stop water from getting in. Be vigilante! 

[OSUAV8TER]

Maintain your o-rings! Even if you don't get them from me! 

[mike_elliott]

7 minutes ago, OSUAV8TER said:

Maintain your o-rings! Even if you don't get them from me! 

the -010 inner o ring is usually the culprit of H20 contamination, as water can pool in the recessed locking tab area of a shaw cap. These are cheap enough they should be replaced every annual, needed or not, and caps adjusted for proper closing. Dow grease should be used to help keep them healthy and "subtle" so they can do their job. If the plane sits outside, this might not be frequent enough. The blue flourosilcone O rings last much longer, and without question are better. Legal? dunno, I hope so. better?  absolutely.

 

[OSUAV8TER]

Just now, mike_elliott said:

the -010 inner o ring is usually the culprit of H20 contamination, as water can pool in the recessed locking tab area of a shaw cap. These are cheap enough they should be replaced every annual, needed or not, and caps adjusted for proper closing. Dow grease should be used to help keep them healthy and "subtle" so they can do their job. If the plane sits outside, this might not be frequent enough. The blue flourosilcone O rings last much longer, and without question are better. Legal? dunno, I hope so. better?  absolutely.

 

The blue fluorosilicone o-rings are legal if installed and signed off correctly. They are military specification parts (considered a standard part) and should be signed off with a logbook entry as a minor modification by your mechanic. I've had my fluorosilicone o-rings on my fuel caps for four years now and I have never had a problem. I still sump my tanks when the airplane sits outside over night. 

You are correct that the inner o-ring is often neglected because it cannot be seen. You have to disassemble the fuel cap to really see what is going on. 

www.gallagheraviationllc.com/products <--- Order fluorosilicone fuel cap o-ring kits

Most Mooney aircraft have the Shaw 431-9R type fuel cap but some also have the Shaw 531-001 or 531-046. All of those fuel caps take the same kit, which is pictured below.