During the cross-country flight, the Cessna 150’s engine experienced a total loss of power and the student pilot performed a forced landing to a field near Simmesport, Louisiana. The airplane nosed over during the landing and came to rest inverted.
An examination of the engine revealed that the incorrect bearing and thrust washer had been used during the engine reassembly about 90 flight hours before the accident, resulting in the seizure and failure of the #1 and #2 connecting rods and the subsequent loss of engine power.
The mechanic who performed the overhaul and reassembly used an outdated parts manual and installed the improper bearing and thrust washer assembly.
Probable cause: The installation of an improper bearing and thrust washer during engine overhaul, which resulted in failure of the connecting rods and a subsequent total loss of engine power.
NTSB Identification: CEN16LA118
This March 2016 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.
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I have 2 thoughts on the assembly of this engine;
1. This 1966 engine and the 1977 parts catalog indicate that the 3 piece bearing was correct for at least 11 years….Did all of the engines built with these parts all fail ? I’m confident that they did not.
2. It appears that the mechanic was not familiar with the TCM O-200 engine, or he would have known to use the latest, approved parts.
My best guess is that the mechanic may not have correctly assembled the engine, and he may be liable for the failure.
But, it did operate for 90 hours. I could guess that the engine may have been run low on oil , and lube starvation caused the bearing to fail.
After reading the inspection results and the photos, I can’t see how a thrust bearing defect can cause the #1 and #2 con rods to break….at the other end of the engine.
dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=59382&CFID=1526242&CFTOKEN=5f3195ac44e15611-1BF822EA-D4E0-D57C-82DA7B19C1F3DB8D
dms.ntsb.gov/public/59000-59499/59382/598254.pdf
Also, after researching the O-200 Overhaul manual, there are 2 crankcases, old and new, which require the use of different front bearing and thrust washers.! If this was an older style engine, then the 5 piece bearing and washers was the correct parts..!
This report looks to have assigned the wrong reason for failure.
Oops. “Trust” is a big deal in aviation. Absent a mishap (like engine failure and a resulting accident…) who would know — i.e. can pilots “verify” correct assembly? Nope! We assume mechanics use current references… but [?]sometimes…