The pilot reported that, during the initial climb after takeoff from Runway 20 at Nut Tree Airport (KVCB) in Vacaville, California, the Cessna 150H’s engine began to sputter while the airplane was about 200 to 250 feet above ground level.
The engine speed decreased to about 1,700 to 1,800 rpm.
The pilot verified that the mixture and throttle were in the takeoff positions, but the airplane was no longer climbing, and he had difficulty maintaining altitude.
As a result, he initiated a forced landing to an open field adjacent to the airport.
During the landing roll, the airplane hit uneven terrain and came to rest upright, resulting in substantial damage to the left wing and fuselage. The pilot and passenger sustained minor injuries in the crash.
Post-accident examination of the engine revealed that it was partially attached to the engine mount. The carburetor was separated from the intake spider.
The upper spark plugs and rocker box covers were removed and the propeller was rotated by hand. Rotational continuity was established throughout the engine. Thumb compression was obtained on cylinder Nos. 1, 3, and 4. No compression was obtained on cylinder No. 2, which was removed for further examination.
The No. 2 cylinder was intact and undamaged. The exhaust and intake valve springs were intact and oil coated, as were the intake and exhaust valve rocker arms.
The valve springs and keepers were removed. The intake valve slid out of the valve guide freely, but the exhaust valve slid out of the valve guide with a significant amount of force.
The exhaust valve stem exhibited carbon buildup along with the valve neck. White deposits were observed around the rim of the valve. The valve seat also exhibited carbon buildup.
The intake valve stem exhibited carbon deposits on the neck of the valve and stem. The valve seat contact area showed no carbon buildup, but a slight amount of carbon build-up was observed on the valve rim.
Probable Cause: The partial loss of engine power due to a stuck exhaust valve.
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This August 2022 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
There is nothing wrong with the looks of those valves, other than bad leaning if not any leaning at all. Those valves are all sooted up because the operator did not lean the fuel well while flying the airplane, some instructors leave the mixture full rich all the time they are teaching students how to fly, never to show the student how to lean properly or lean at all. I know a few instructors that tell me they don’t show their students how to lean because they say they have to many other more important things to learn. HaHa, that is whats wrong with those valves you show a picture of, they are very sooty indicating the mixture was never leaned at all, that leading to carbon build up and causing problems, thats all that is wrong with that picture. Carless CFI not teaching all there is to flying !!!
What’s more important than a sticking valve on your engine? A sticky mitro-valve in your heart, e.g., “MYOCARDITIS” – which is brought on by the jabs and boosters. Don’t become another “safe and effective” victim-statistic. Refuse the jabs and the boosters.
James Brian Potter, 35 thousand people are killed every year on American highways in auto accidents. Do you use energy/matter transportation to go to work and the grocery store?
Using the NTSB data, the calculated auto death rate is 25 per 100,000 hours.
https://www.bts.gov/statistical-products/surveys/national-household-travel-survey-daily-travel-quick-facts
By contrast, the FAA data has fatal GA crashes at 0.8 per 100,000 hours.
https://www.bts.gov/content/us-general-aviationa-safety-data
So, from this it’s 25x more hazardous to drive a car vs fly a GA aircraft.
90% of day , vfr, off airport landing are survivable [ ie; crashes ]
I’m neither pilot nor airplane owner but have friends who are GA airplane owners. They are well-to-do and perform the regular scheduled maintenance on their airships, including having the engine oil evaluated for metal content, replacing engines, etc. But after reading stories like this for years on this news service, it seems to me that a GA flight — even with pre-flight checks and mechanical diligence — still constitutes a risk to life; a crap shoot as to whether or not the whole flight from takeoff to landing will be uneventful. Not a hobby I will ever partake of.
Regards/J
J Potter,
Guess you should never get on a bus, train, bicycle, skates, skateboard, boat, kayak, or motorcycle either.
Just stay home and be “safe”.
Keeps happening and will keep happening until the lead in fuel is gone
I personally have had four stuck valve events. Two in the air and two on the ground, all in small continental engines
Do not use any oil that is half synthetic use
Marvel mystery oil in the fuel and Camguard in the oil. Change oil every 25 hours. Lean properly
Auto fuel with an STC is available with no ethanol
Regards
That so called “carbon” build up is lead. Doesn’t happen unless you run 100LL. Thousands of light aircraft engines are damaged very day with leaded fuel and has been happening ever since the demise of 80/87 fuel. But the professional foot draggers still keep throwing roadblocks in the way of moving away from 100LL because we must have a one fuel drop in replacement.
It would be interesting to know the lead content of those deposits.
With my oil use down to 12 hrs per qt, the lead levels in the oil jumped to 3,000 ppm. About 100 hrs later, after a couple of 50 hr oil changes, I found 3 stuck exhaust valves, on cold start , thankfully.!
I’m now doing 25-30 hr oil changes which gets the lead level down to about 1,200-1,500 ppm , like when the engine was using a qt every 3-4 hrs.
Obviously, the lead levels build up over the hours , with the blowby.
From the engine pic I noted that #2 cylinder, [ pilot side, rear ], is badly discolored, indicating very high cylinder head temps.
I also see that part of the rear baffle is missing. That will greatly reduce the cooling to #2 cylinder. [ assuming that it wasn’t damaged during the inspection ?]
Both Continental and Lycoming will get lead- bromide deposits on the exhaust valve guide, typically from the deposits in the oil.
Lycoming has a service bulletin requiring to check for valve sticking every 400 hours.!!
https://www.lycoming.com/content/service-bulletin-no-388c
https://www.lycoming.com/content/service-instruction-no-1425a
Ignore it at your own risk.!!
My Continental had 3 valves sticking open after our oil use dropped to about 11 hrs per qt., and about 100 hrs later.! I lean aggressively during all operations. This has only happened since the low oil use. The engine has 1,800 + hrs on it, with about 350 hrs on the cylinders.