The private pilot reported that the personal local flight was uneventful until the engine made an odd noise, which was followed by a partial loss of engine power.
He attempted to troubleshoot the problem, but the engine power was not fully restored, and the Piper PA-28R was unable to maintain altitude, so he made a forced landing to a road near Bayonne, N.J.
The plane struck power lines and vehicles before coming to rest on a sidewalk. The pilot was seriously injured in the crash.
Post-accident examination of the engine revealed that the No. 3 cylinder’s intake valve had separated. The valve stem was found in the oil pan, and the remainder of the valve was found in its intake manifold.
Metallurgical examination of the No. 3 cylinder assembly, including the fractured intake valve, revealed that the valve was fractured in the stem in two places and through the head in one place. The interior of the cylinder exhibited damage consistent with impacts from the fractured valve. The connecting rod was intact, but the bearings were worn through both the babbit and copper layers.
Examination of the fracture surfaces revealed fatigue cracks initiating from the fillet radius between the valve stem tip and the key area of the stem shaft. The other fractures were consistent with overstress.
Further examination of the engine case revealed that all eight hydraulic valve tappet plungers were installed 180° opposite of the proper installation contained in the manufacturer’s overhaul manual. The reversed installation of the plunger would have adversely affected the operation of the No. 3 cylinder’s intake valve and placed an abnormal load on the valve’s tip.
A review of the engine’s maintenance logbook revealed that the engine had been repaired about 35.7 hours before the accident. At that time, all four cylinders were removed and replaced, including the hydraulic valve tappet plunger assemblies.
Given that the cylinders had been recently removed and reinstalled on the engine, including the hydraulic valve tappet plungers, it is likely that the engine experienced a partial loss of engine power due to maintenance personnel’s improper installation of the No. 3 cylinder’s hydraulic valve tappet plunger.
Probable cause: Maintenance personnel’s incorrect installation of the No. 3 cylinder’s hydraulic valve tappet plunger, which resulted in a failure of the No. 3 cylinder’s intake valve and the subsequent partial loss of engine power.
NTSB Identification: ERA17LA110
This February 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.
Unfortunately we all can’t afford the time and/or money to go to A&P School and then spend years as an apprentice to earn a maintenance certificate. We have to find a shop we can trust by word of mouth or reputation. As with any sort of repair, whether it be your car, airplane, or house, it is a good idea to learn as much as you can so that you can make a decision as to whether the person you are dealing with knows what he/she is talking about.
I don’t follow this evaluation very well. How can a hydraulic tappet effect the valve stem keeper key area. There are 12″ long push rods between those to components. Did I miss something in the dialog.
I have seen when after a replacement of all cylinders where a valve failed in the same fashion in a Lyc. engine. The engine mfr’r claimed the used reground cam shaft caused the problem on only one cylinder after some 40+ hours after a complete overhaul.
The true reason was the valve stem keeper groove being ground at to high a tempture causing striations in the stem keeper grooves. However, only one failure was noted. It was just bad parts from Lyc.
The lifter assembly is in 2 parts, and the inner, hydraulic piston was installed with the socket end inward. It should have been very obvious that they were installed incorrectly.
see. the docket photos..https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=60811&CFID=2400040&CFTOKEN=820a7284ac6fbfd6-D8879DC9-BCB1-8D10-5C6D4706583B1E18
I’m surprised that this engine ran at all, and that the rockers got any oil.
The mechanic who did this work should lose his A&P cert.,
This was a rental aircraft, so the pilot won’t know who worked on it.
Just a reminder to vette the shop that does your maintenance. I once trusted a maintenance facility that until I questioned a procedure, their it’s “good enough” response terminated that relationship. Too many shops only want the expensive fees they can charge for work in aviation. They forget or don’t care that we have our necks on the line. If you have found a good shop you trust, share that information with your circle of pilots. I have yet to find someone I completely trust.
…and THAT is the reason I earned an A&P more than 40 years ago and NO ONE touches my airplanes except for me, Dave. Not only do I trust my own maintenance, I know the “weak” spots of my airplanes and treat them accordingly. Also, I get better maintenance because I afford the time and cost of doing it 110%.