What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
On 7/28/2022 at approximately 1435 local time privacy data omitted reported a rough running engine to ATC and declared an emergency. The pilot attempted to divert to krbd airport but advised he was not able to make the airport and would land in the trees. The aircraft came to rest in a wooded area approximately 2,300' to the southwest of the threshold to runway 35.
On scene investigation showed the aircraft was destroyed with the left wing separated from the fuselage after impact with the trees, right wing bent aft and up and the cockpit cut open from fire rescue during pilot extraction. One propeller blade could be seen with a straight tip indicating engine was not rotating on impact. Interview of first responders indicated a strong fuel smell was present when they arrived on scene. Maintenance logbooks were in the aircraft and recovered as part of the investigation. Pilot was not able to be interviewed due to incapacitation at the hospital. Review of video posted to social media purportedly showed the aircraft enroute with popping sounds heard prior to the accident.
Magneto removed for further examination and testing. Cam follower on right side observed melted with no contact point clearance. No melting was observed on left side but contact point clearance was noted out of tolerance at 0.008 in. Review of D-3000 series magneto service support manual noted contact point clearance on the left main is supposed to be set at 0.016 +/- 0.002 in.
Various bench tests were performed to isolate the issue. During testing, it was found that both capacitors functioned properly but due to corrosion around the magneto casing on both the inside and outside where the capacitor was installed the capacitor was not grounding correctly. The magneto performed normally when an additional grounding jumper was installed from the capacitor direct to ground for both capacitors. When the additional jumper wire was removed simulating the installed condition and operating off the left capacitor very intermittent ignition was observed. With that same configuration while operating off the right capacitor no ignition was seen and arcing was observed at the contact points which led to melting of the cam follower.
Review of teledyne Continental service bulletin SB651 states "high resistance or discontinuity between the capacitor and the remainder of the magneto will result in destruction of the contact assembly, loss of ignition, and loss of engine power". It further states that "if either the ground return path or the flag terminal lead path presents high resistance, arcing will occur at the points. Arcing causes the points to overheat, which also overheats the spring to which one of the points is attached. The nylon cam follower then melts where it bears against the hot spring".
An invoice was found with the maintenance records for a 500 hr inspection on the magneto with invoice date of 05/22/2021 and a tach time 0.4 hours prior to the tach time noted at the accident scene.
As the FAA filed it
ON 7/28/2022 AT APPROXIMATELY 1435 LOCAL TIME ^PRIVACY DATA OMITTED^ REPORTED A ROUGH RUNNING ENGINE TO ATC AND DECLARED AN EMERGENCY. THE PILOT ATTEMPTED TO DIVERT TO KRBD AIRPORT BUT ADVISED HE WAS NOT ABLE TO MAKE THE AIRPORT AND WOULD LAND IN THE TREES. THE AIRCRAFT CAME TO REST IN A WOODED AREA APPROXIMATELY 2,300' TO THE SOUTHWEST OF THE THRESHOLD TO RUNWAY 35.
ON SCENE INVESTIGATION SHOWED THE AIRCRAFT WAS DESTROYED WITH THE LEFT WING SEPARATED FROM THE FUSELAGE AFTER IMPACT WITH THE TREES, RIGHT WING BENT AFT AND UP AND THE COCKPIT CUT OPEN FROM FIRE RESCUE DURING PILOT EXTRACTION. ONE PROPELLER BLADE COULD BE SEEN WITH A STRAIGHT TIP INDICATING ENGINE WAS NOT ROTATING ON IMPACT. INTERVIEW OF FIRST RESPONDERS INDICATED A STRONG FUEL SMELL WAS PRESENT WHEN THEY ARRIVED ON SCENE. MAINTENANCE LOGBOOKS WERE IN THE AIRCRAFT AND RECOVERED AS PART OF THE INVESTIGATION. PILOT WAS NOT ABLE TO BE INTERVIEWED DUE TO INCAPACITATION AT THE HOSPITAL. REVIEW OF VIDEO POSTED TO SOCIAL MEDIA PURPORTEDLY SHOWED THE AIRCRAFT ENROUTE WITH POPPING SOUNDS HEARD PRIOR TO THE ACCIDENT.
MAGNETO REMOVED FOR FURTHER EXAMINATION AND TESTING. CAM FOLLOWER ON RIGHT SIDE OBSERVED MELTED WITH NO CONTACT POINT CLEARANCE. NO MELTING WAS OBSERVED ON LEFT SIDE BUT CONTACT POINT CLEARANCE WAS NOTED OUT OF TOLERANCE AT 0.008 IN. REVIEW OF D-3000 SERIES MAGNETO SERVICE SUPPORT MANUAL NOTED CONTACT POINT CLEARANCE ON THE LEFT MAIN IS SUPPOSED TO BE SET AT 0.016 +/- 0.002 IN.
VARIOUS BENCH TESTS WERE PERFORMED TO ISOLATE THE ISSUE. DURING TESTING, IT WAS FOUND THAT BOTH CAPACITORS FUNCTIONED PROPERLY BUT DUE TO CORROSION AROUND THE MAGNETO CASING ON BOTH THE INSIDE AND OUTSIDE WHERE THE CAPACITOR WAS INSTALLED THE CAPACITOR WAS NOT GROUNDING CORRECTLY. THE MAGNETO PERFORMED NORMALLY WHEN AN ADDITIONAL GROUNDING JUMPER WAS INSTALLED FROM THE CAPACITOR DIRECT TO GROUND FOR BOTH CAPACITORS. WHEN THE ADDITIONAL JUMPER WIRE WAS REMOVED SIMULATING THE INSTALLED CONDITION AND OPERATING OFF THE LEFT CAPACITOR VERY INTERMITTENT IGNITION WAS OBSERVED. WITH THAT SAME CONFIGURATION WHILE OPERATING OFF THE RIGHT CAPACITOR NO IGNITION WAS SEEN AND ARCING WAS OBSERVED AT THE CONTACT POINTS WHICH LED TO MELTING OF THE CAM FOLLOWER.
REVIEW OF TELEDYNE CONTINENTAL SERVICE BULLETIN SB651 STATES "HIGH RESISTANCE OR DISCONTINUITY BETWEEN THE CAPACITOR AND THE REMAINDER OF THE MAGNETO WILL RESULT IN DESTRUCTION OF THE CONTACT ASSEMBLY, LOSS OF IGNITION, AND LOSS OF ENGINE POWER". IT FURTHER STATES THAT "IF EITHER THE GROUND RETURN PATH OR THE FLAG TERMINAL LEAD PATH PRESENTS HIGH RESISTANCE, ARCING WILL OCCUR AT THE POINTS. ARCING CAUSES THE POINTS TO OVERHEAT, WHICH ALSO OVERHEATS THE SPRING TO WHICH ONE OF THE POINTS IS ATTACHED. THE NYLON CAM FOLLOWER THEN MELTS WHERE IT BEARS AGAINST THE HOT SPRING".
AN INVOICE WAS FOUND WITH THE MAINTENANCE RECORDS FOR A 500 HR INSPECTION ON THE MAGNETO WITH INVOICE DATE OF 05/22/2021 AND A TACH TIME 0.4 HOURS PRIOR TO THE TACH TIME NOTED AT THE ACCIDENT SCENE.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.
Other reports on N3027J · 2
Matched to the same aircraft by N-number and date.