The private pilot and a passenger planned to depart on a cross-country personal flight in the Piper PA32R from the airport in Falcon, Colorado, where density altitude was about 9,500 feet mean sea level.
During the pretakeoff engine run-up, the engine began running roughly. The pilot and a mechanic attempted to troubleshoot the engine issue by checking the dual magneto.
According to the mechanic, the left magneto was inoperative and the P-leads were wired incorrectly. He then disconnected both magnetos’ P-leads.
The pilot’s second and third engine run-ups appeared to produce full engine power when he adjusted the fuel mixture, however with an inoperative left magneto it is unlikely that full power was achieved.
The pilot departed and was unable to maintain altitude. He chose to land in a field adjacent to the airport. The airplane stalled just above the ground and then hit the ground.
During a post-accident examination of the airplane, the left magneto was removed and tested. It did not produce a spark at any terminal, and the contact points did not open.
Additionally, the spark plugs connected to the left magneto did not exhibit signs of recent operation, which was consistent with an inoperative magneto.
The disconnected P-leads would not have affected the right magneto’s ability to energize half of the spark plugs.
With an inoperative left magneto and a high density altitude, the available engine power would have been reduced, and the airplane’s climb performance would have been degraded.
The reduction in the available engine power, combined with the high-density altitude at the time of takeoff, resulted in the airplane’s inability to maintain a positive rate of climb after lifting off.
Probable cause: The pilot’s decision to depart with an inoperative left magneto, which resulted in degraded climb performance in high-density altitude conditions and a subsequent emergency landing.
NTSB Identification: CEN18LA348
This August 2018 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.
Manny Puerta says
At high density altitudes there’s no greater, comforting feeling than one “mag” being Electroair electronic ignition that advances at lower manifold pressures and the other a Bendix 1200 series overhauled every 500hrs by Aircraft Magneto Service in Missoula, MT or Aircraft Electrical Components in Redding, CA.
The only Bendix mag issue I ever had was “technician” induced or someone else’s airplane with sketchy attention to maintenance.
Henry K. COOPER says
Having swung wrenches all during the ’70’s and the early ’80’s, the only magnetos I had trouble with were the small Slick “throw-away” mags on TCM 0-200 engines in the C150. They could not be disassembled and inspected or adjusted, and were replaced on condition, which seemed to average about 500-600 hours. All the “big” Slick 600 series and the Bendix mags could he inspected, adjusted, and lubed as part of any 100 hour or annual inspection. I could easily get a full engine run out of them. Even with all the reported troubles with the D2000 mags, with repeated service letters and bulletins, I complied with each to the point that I could do it in my sleep. Yes, I found issues and repaired or replaced parts, but I never had an in-flight incident with any of them.
Henry K. Cooper says
Sounds as if the dual mag hadn’t had its cap removed and hadn’t been inspected for some time. Likely the hold down screw for the points adjustment for the left mag came loose. No left mag means an unairworthy aircraft, which the pilot decided to fly anyway….with a passenger. A dumb decision, and illegal, too. Why the mechanic decided to remove the P-leads from the mag is beyond me. Normally, removing P-leads would only make both mags hot, and wouldn’t affect operation in flight, but all this brings to mind a lesson I learned long ago.
When you remove P-leads from a D2000 mag, the engine will start and run fine…..for awhile. On the mag, inside the ferrule that the P-lead screws into is a spring. This spring is normally depressed by the P-lead “cigarette” in order to make a positive electrical contact. When the P-lead is removed, this spring is unloaded and vibrates around inside the ferrule. If it contacts ground, it will make the mag fire erratically, or not fire at all.
Wylbur Wrong says
I looked up this aircraft. It looks to me to be a Saratoga retract, non-turbo. That being the case, this has an IO540-K1G5D (same as the one I now fly). This engine is the same as the Cherokee-6 300 and Lance. It has “suicide mags” (I think those are the D2000 as Henry stated). And you can have them working on the ground and they can fail in the air. Were they incorrectly wired? Need to talk to the prior A&P that worked on that engine.
N2920Q — Look it up. Dual Mag failure in flight. My partner landed it in a Dick’s Sporting Goods store parking lot. NTSB still can’t tell us what was wrong with those mags, and the engine and mags had less than 100 hours since Major Overhaul (engine, prop governor, prop, mags). After the lab “reset them” they both produced spark again, but they did not produce spark on initial test after checking the engine once it was in a maint hangar.
Henry K. Cooper says
One thing to check, as I remember, is the part number of the coils that are installed. I recall that some 6-cylinder D-2000 mags had been manufactured using 4-cylinder coils, which look nearly identical and fit in the housing the same way. They’d spark fine on the bench, but would fail in operation on the engine…..heat, most likely. I can’t imagine that after over 40 years, these coils wouldn’t have been discovered and removed.
Miami Mike says
“If it ain’t broke, don’t fix it (remove P lead from working mag), if it ain’t fixed, don’t fly it (and wind up crashed in a field).”
Will Rogers said “There’s two types of people in the world. Those who learn from the mistakes of others, and those who only learn by p*ss*ng on the electric fence themselves.”
If you want to live a long and happy life, strive to be a member of the first group. This goes double if there are airplanes involved.
IA from Ohio says
2 Slick mags overhauled by Kelly Aerospace. 131 hrs later, left mag drop 200+, right mag OK. Opened left and right mags to inspect. Left mag cam lobes worn down to a pile of dust below the shaft. Right mag not worn. Both mags had excessive carbon material coming off the brush. Sent to Kelly for out of warranty repair. They did replace the parts, will wait to see if problem re-occurs. Kelly makes their own replacement parts for Slick mags. Filing SDR.
JimH in CA says
I’ve had both magnetos fail over the last 6 months, the right mag in feb. and the left mag in july. Both had gotten their 500 hour inspections and any repairs. Both failed with an open ignition coil.
The engine log showed that both were replaced with new 6367 Slick mags 1,550 hours ago, so no surprise that failed so close together.
Both mag failures were found during the run up, and caused me to taxi back to my hangar and shut down.
I now do a mag check shortly after engine start, once the cylinder temps come up.
I had the mags. rebuilt vs overhauled, since a rebuild returns the mags to new, ‘0’ time, with all internal parts being replaced. I used QAA, Quality Aircraft Accessories in Tulsa, OK…..good folks and great service.
I’m waiting for a ‘SureFly’ electronic ignition unit to be certified for my engine, a TCM GO-300.
Roger Overandout says
Of note.. disconnecting a magneto’s P-lead removes the grounding connection and makes the magneto operative (“hot”). The mechanic may have known this and did it to eliminate faulty wiring as a possible source of the trouble. But his initial diagnosis that the wiring was wrong was not necessarily correct. Sounds like they were in a hurry, wanted to get underway, and fooled themselves into thinking it was working normally.