On May 6, 2019, a Piper PA-28-140 was destroyed when it hit terrain shortly after takeoff from Foley Municipal Airport (5R4) in Alabama. The flight instructor was seriously injured, and the student pilot was killed in the crash.
According to a witness, who was a flight paramedic on another instructional flight at the airport, he saw the Piper take off from Runway 36 after a touch-and-go landing. He then heard the flight instructor announce on the radio, “My engine just quit.”
He saw the plane pitch up “like a power-on stall” then “lean to the left to start a spin” about 300-400 feet above ground level (agl). He added that it was only about three seconds from the time he saw the airplane in a nose-high pitch attitude to when it was descending toward the ground.
A flight instructor who was entering the traffic pattern at 5R4 reported that the airplane seemed to be making an aggressive left turn as if returning to the airport.
According to another flight instructor who flew the airplane the morning of the accident, the plane “didn’t seem to climb very well,” which he attributed to high density altitude. He stated that, at the time of the accident, the flight instructor in the Piper was conducting simulated engine-out emergency procedures in the pattern as touch-and-go landings. The instructor added that he had previously shared a flight student with the accident flight instructor. That student used a “two-swipe” pitch trim method during the landing flare that the accident flight instructor had taught him: Just before flaring the airplane for landing, the student rolled the pitch trim wheel twice in a nose-up direction.
A different flight instructor who flew the airplane the day before the accident reported that he experienced engine roughness when performing simulated engine-out procedures with a student. He stated that on the last simulated engine-out procedure, when he added power at 600 feet agl, the engine started shaking. He leaned the mixture and the engine ran smoothly again. He wrote up a maintenance ticket when he landed and stated that the mechanic cleaned the spark plugs, performed an engine run-up, and signed off the maintenance write-up. The instructor subsequently flew the airplane and noted no issues.
The 1255 recorded weather observation at Sonny Callahan Airport in Fairhope, Alabama, about eight miles west of the accident, included wind from 270° at 3 knots, 10 miles visibility, clear skies, temperature 26°C, dew point 17°C, and an altimeter setting of 30.03 inches of mercury.
Examination of the accident site and wreckage revealed several impression marks on the ground along a 243° heading. The airplane came to rest upright on the edge of airport property. All major airplane components were located at the site. The left wing was separated from the fuselage at the wing root and came to rest inverted 18 feet from the main wreckage.
The empennage was crushed and folded inverted along the left side of the passenger cabin. The vertical stabilizer was attached and bent 90° to the right at the attachment points. The rudder remained attached and was bent and impact damaged along its entire length. The outboard three feet of the right stabilator was crushed and the left side of the stabilator and trim tab was undamaged. The top of the fuselage aft of the front seats was folded back on top of the aft cabin. The forward end of the fuselage, including the instrument panel, forward cabin door, firewall, and engine, were folded down and under the forward cabin floor. The engine remained attached to the mount.
The left wing, including the attached flap and aileron, was fractured and damaged on all surfaces. The fuel tank was breached, and the grass around the wing displayed fuel blighting. The landing gear was fractured off and connected by the brake hose. The right wing, including the attached flap and aileron, was crushed from the wingtip to mid-wing and displaced upward with multiple fractures. The outer two feet of the flap was crushed in a negative direction, and the inboard two feet of aileron was fractured, bent, and crushed.
Examination of the airframe revealed no preimpact failures of any flight control surface or flight control system components.
The engine and its accessories were examined. The top spark plugs were removed, and visual examination revealed no anomalies. The rocker box covers were removed, and no anomalies were noted with the valve springs and rocker arms. Manual rotation of the engine’s crankshaft produced compression on all four cylinders. The left and right magnetos were removed, and sparks were observed on all towers when each magneto was rotated by hand.
Examination of the cylinders with a lighted borescope revealed a circular impact mark consistent with an exhaust valve strike on the No. 4 piston. The No. 4 cylinder was removed from the crankcase. The rocker arm, valve keepers, and springs were removed. The exhaust valve could not be removed from the valve guide by hand and was removed utilizing a hammer and a drift. The exhaust valve exhibited combustion deposits on the stem close to the rear of the valve face. Carbon build-up was observed in the valve guide.
Review of the accident airplane maintenance logs revealed that the No. 4 cylinder had accumulated a total of 591.85 hours since replacement with an Engine Component Inc. (ECI) Titan cylinder. ECI does not offer guidance regarding the frequency of inspection of the Hi-Chrome valve guides in order to detect valve sticking. A valve inspection was not performed after the flight instructor reported engine roughness the day before the accident.
Probable Cause: A partial loss of engine power due to a stuck exhaust valve and the flight instructor’s exceedance of the airplane’s critical angle of attack following the loss of power, which resulted in an aerodynamic stall at low altitude.
An unresolved maintenance issue led to a power loss, that was not handled successfully. This CFI failed to reduce AOA promptly, (maybe due to the startle effect) and this caused the airspeed to decay until the stall and incipient spin began. “Unloading” has to be a trained reflexive action in all pilots (contrary to human “pull-up” reaction). Sad outcome.
This May 2019 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.
Be ready! https://safeblog.org/2021/05/08/priming-enables-performance/
Unloading. An absolute must for all pilots who experience stall speeds!
That instructor should have pushed forward on the yoke and they wouldn’t have stalled.
Yes, if they could. I have had a plane in this situation at altitude doing slow flight practice. And this is how you demo this problem:
Set up as if you are going to do a full stall landing and then you have to go around.
You go full throttle while flying straight but set up for a full stall landing (lots of nose up trim here).
Applying full throttle causes the elevator/stabilator to have more authority and now you have to shove that yoke in, and, get that trim back to something close to neutral. If you don’t have the strength you have to put it into a turn to keep it from stalling. And if you don’t get it right, you stall spin even at altitude (you do this at an altitude where you can recover.).
It is an eye opening experience. You have to trim towards neutral before full throttle.
The engineer at ASL Camguard has a great analysis of what the deposits are and how to greatly reduce them.
https://aslcamguard.com/sticking-exhaust-valves/
It is most important to lean the mixture after a cold start and taxiing, to keep the exhaust gas temps high enough to prevent the lead salts from condensing on the exhaust valve stem.
Piloting aside, here is but another story about a Lycoming engine certified for 80/87 AvGas having stuck exhaust valves when using 100LL. Back when 80/87 was phased out, within 6 months, our Cessna 172L and M fleet began experiencing stuck valves, bent pushrod and tubes. Using a lead scavenging fuel additive was no help. The only remedy I found to be effective was to drop the exhaust system, and remove the exhaust valve within the cylinder using strong mechanical fingers, then ream the guide. I’d do this about every 300 hours. All sorts of nastiness came out. I won’t get into the issues with small TCM engines that had to drink 100LL.
I certainly won’t disagree with you on maintenance issues as I too have “been there,done that” with lead issues.
However like me you must not understand that we all “NEED” 100LL. Why can’t we just get 94UL, easy to make,just leave the lead out, no STC needed and so many problems would go away.
Every pilot should study their home airport(s) and know where they can put their plane down. CFI in particular.
On take-off the pitch attitude is 3 to 10 degrees nose up. AOA is slightly less.
If the engine fails the pitch attire MUST be reduced to a3 to 5 degree nose down.
Land somewhere in an arc 45 degrees L or R of straight ahead.
Trainers such as this PA28 are subject full rich and sudden power changes. Valves, spark plugs and oil take a beating.
A&Ps should pay attention to oil, spark plug and valve guides.
Fly some short Scans lean the engine. Look all the time where you are and pick places to land.
Demo a 270-90 turn to simulated an engine failure at 3 to 5000 feet AGL. Start w/o the engine failure, just doing the turn. Then reduce power to 1800/2000 RPM.
When you simulate engine failure don’t forget to use carb heat.
At pattern altitude or lower you have to pitch down to glide attitude. No time to look at a checklist.
Absolutely agree! Knowing your home airport and the surrounding area may not guarantee a 100% successful outcome from an engine failure, but having a specific plan(s) tailored to, and practiced at, your airport, is way better than a canned “if we’re below 1,000’, we’ll land straight ahead…”. If that means landing on a golf course, you should know which hole you’re aiming for.