The flight instructor reported that, after takeoff, when the Piper PA-28-140 was about 500 feet above ground level, the engine started to run roughly and lose power.
Engine rpm decreased to about 1,100 as he attempted to turn the airplane 180° back toward the airport in Granbury, Texas. However, he was unable to land at the airport, so he made a forced landing to a field short of the runway.
During a post-accident engine test run, the engine initially ran roughly, and black smoke was observed coming from the exhaust.
After a brief warmup, the engine could only produce about 1,600 rpm at full throttle, and the engine test run was stopped.
Examination of the No. 3 cylinder revealed that the exhaust valve was broken in several pieces and that some fragments remained in the cylinder, which produced gouging and scraping to the piston and cylinder head.
The broken exhaust valve, spring, exhaust valve keepers, and rotating cap exhibited carbon buildup.
Examination revealed a wear pattern on the top of the No. 3 cylinder exhaust valve rotator cap consistent with rocker arm wear. No rotational signatures were observed along the edge of the cap near the heavy carbon buildup, indicating that the rotator cap had stopped rotating, which subsequently led to a hot spot on the exhaust valve and caused the valve to fail.
The NTSB determined the probable cause as the partial loss of engine power due to the failure of the exhaust valve.
NTSB Identification: CEN14LA334
This July 2014 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.
We had >100 hrs. on a set of new Lyc. cyl.(s) on a IO 540 Piper PA 30. The # 3 exhaust upper valve stem failed at the keeper lands. Valve dropped into cyl. and broke into three pieces and then stem went thru head. Engine kept running and made it home over mountains at night. Power was somewhat reduced but never adjusted the throttle or pitch control until runway was made. Lyc would not stand behind their inferior parts and had to be sued to recover funds for another overhaul.
I lost a cylinder in a 172, Lycoming 032, 150 hp. I was able to climb about 50 rpm at 1900 rpm. A broken valve trashed 1 cylinder. This Cherokee made 1600 rpm static, so 1900 in flight is possible. I suspect the instructor was not well practiced in slow flight. I’ll bet you can maintain altitude in a Cherokee at 1900 rpm. Would be an interesting experiment for a Cherokee driver.
You are so right, been there also only in a 150
over muskeg country, but sure had clammy hands.
thank heavens we made it to safe landing
I AM the pilot for that incident 3 years ago. My student was great, calling mayday, and announcing my altitude and airspeed. I don’t know how I got over those power lines and slammed into the road shoulder, right wing hit a tree and spun to the right. the running propped shaved a very nice hedge on the next sapling. sliding sideways, the tail hit a tree, the left wing hit drooping oak limbs and we came to a stop,,, in about 50 feet. both of us walked away,,, I went back to my faith. In 3 months, I will be eligible for the Wilbur Wright award,,, I hope this doesn’t rain on my party. Jim Zoeller, CFI-I, ATP
James: The accident report and your FAA Form 6120.1 from the Docket are very interesting. Thanks for contributing to this discussion, and congratulations for a successful landing (one with no injuries!!!) in very difficult circumstances.
I’m curious whether you had previously practiced a low altitude return to an airport under simulated engine failure conditions, and if you briefed the situation prior to takeoff. The docket doesn’t include any aerials of the area, nor the coordinates of where your aircraft came to rest. Did any off airport options exist had you landed without attempting a return to the airport? I have practiced that maneuver in various C172 and C182 aircraft that I fly. I have found it a challenging feat even when mentally prepared, especially if below 800-1000′ AGL.
FWIW, I don’t think an accident where the ‘defining event’ was equipment failure that is handled so well would reduce your opportunity to join the ranks of the FAA’s Wright Brother’s Master Pilot Award recipients. Just my opinion, but that’s how I believe the criteria read.
Been there, had that happen with our 1959 C-172 with the O-300 engine. The exhaust valve broke in two and the larger piece stayed inside the cylinder, creating a bit of havoc. The difference was with five remaining cylinders producing power, even though it’s only 145 HP to begin with, the plane was able, with three adult men inside, to climb at 200 FPM and get us to a normal landing at the closest airport, which was about 5 miles away. It felt like the engine was coming off the mounts, but everything held together and got us down safely.