After takeoff for an instructional flight, when the Cessna 172 reached 1,800′ mean sea level, the student pilot began a left turn toward the destination.
Shortly after, the engine went silent and stopped producing power.
The flight instructor took control, slowed the airplane, and landed into the wind on a gravel road near Algona, Iowa.
During the landing roll, the left wheel caught the edge of the road, and the airplane veered into a ditch, which resulted in substantial damage to the wing and fuselage.
Examination revealed that the engine’s No. 1 cylinder head had separated at the cylinder head-to-barrel interface.
The engine had accumulated 605.9 hours since the last engine overhaul, which was conducted over 23 years before the accident. The engine manufacturer’s recommended time between overhaul for the accident engine was 1,800 hours or 12 years.
However, it could not be determined if the lack of an overhaul within the manufacturer’s recommended overhaul period led to the No. 1 cylinder head separating at the cylinder head-to-barrel interface.
Probable cause: The No. 1 cylinder head separating at the cylinder head-to-barrel interface and the subsequent total loss of engine power.
NTSB Identification: CEN18LA051
This December 2017 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.
John,
It sounds like you’ve had some experience with cylinders.
You mention old vs new part numbers. Do you have info on TCM cylinders ?
I know ECi had a problem about 1999 with head separation…A good friend had an emergency when a head separated. He got on the ground ok, but in helping tow the aircraft off the runway it lost most of the oil.
Personally, I’ll pay the added cost for a new cylinder assembly. It’s still less than a wrecked aircraft during an off airport landing.
The docs state that the engine, with 2,300+ hours TT was ‘overhauled’ 600 + hours before the cylinder failure. The engine and aircraft were mfg. in 1958.
But, the cylinders were reused with new pistons, rings, bearings, etc. So, these cylinders may be 2,300 hrs and 59 years old, with a bunch of new parts.
I would not trust the 59 year old cylinders.
We do top OH on our engine, but I insist on using new cylinder kits, and will not reuse or rebuild old cylinders. We did that with 2 cylinders and after 300-400 hours they developed cracks around the spark plugs.
New cylinders do cost $400-$500 more than a rebuild, but what is your aircraft worth and possibly injury to you ?
The aircraft had a total of 6080.8 hours, the engine a total of 2,351.8 hours since new and 605.9 hours since the last engine overhaul.
There was insufficient information contained in the accident report to come to any conclusion about the history of the failed cylinder. We do not know the total time on the cylinder, nor its part number, which has a significant bearing on its durability. Later cylinders being more robust.
Cylinder failures can be the result of many factors which include, high cylinder head temperatures, extended high power operation, poor baffling causing hot spots, shock cooling, incorrect magneto timing, intake leaks and the less durable cylinder head to barrel joint found in earlier cylinders. Sometimes just the bad luck of an fatigue inducing flaw, such as a poor thread fit or profile or a casting inclusion.
I see no question of reliability using a properly overhauled later part number cylinder in an O-300 engine. My present practice is to use new at overhaul unless the existing cylinders are relatively low time and of a desirable part number.
23 years ago when this engine was overhauled there was a greater divide between the cost overhauling cylinders and replacing them than there is today.
I do not agree with the Safety Board suggestion that because the engine was not overhauled within the 12 year limit it may have been a factor in the head separation. That is nonsense. This limit has more to do with the possibilities of internal corrosion, deterioration of rubber items and of course, lawyers.