Narrative:

An instrument flight plan was filed from cmx to 8d4 in a twin small transport. When my passenger arrived, they said they wanted to make an intermediate stop at iron mountain, mi. Another WX briefing was received just prior to departure, but it indicated this stop was not possible due to thunderstorms in that area. The original flight plan was used, allowing for a deviation to the east to avoid heavy WX. After takeoff, center said that most aircraft in the area were diverting east, and that I could do so too, if I desired. That information agreed with the briefing earlier, so that is what I did. Onboard WX radar was used for thunderstorm avoidance. Even so, it was a rough ride, and I frequently slowed the aircraft to maneuvering speed. I saw lightning close by once, but I didn't know the aircraft was struck until the post-flight inspection. All avionics continued to work normally. About 10 mins later, now in VMC, the right engine failed. The engine was feathered, the checklist performed and ATC notified. Through the center controller my company was phoned and advised of the existing mechanical failure. Position at the time of failure was 59 DME north of white cloud VOR, altitude 13000' at 64% power. Runup at cmx was normal as were all engine gauges. The flight was continued to the destination west/O further incident. The IFR flight plan was closed 3 mi north of the airport, with an uneventful approach and landing. Post-flight inspection of the aircraft revealed external damage to the engine. There is a hole on top of the engine where both case halves are broken. Pieces of piston were found in the engine compartment. Lightning damage is a small hole in the radome, small holes in both fiberglass leading edge fairing adjacent to the fuselage, and a burned area in the top training edge of the rudder where the lightning apparently exited. The opinion expressed by the director of maintenance and the inspector from the insurance company is that lightning caused damage resulting in an engine failure a short time after the strike. The insurance company said our claim was the fifth aircraft lightning strike claim made to them concerning aircraft lightning strikes in that WX system that day. Callback conversation with reporter revealed the following: reporter stated that he was about 5 mi from the cells on the radar, utilizing an X band radar set. Post-flight inspection revealed the damage and maintenance found that both engines were magnetized by the lightning strike. An analysis of the parts led to a theory that the valve guide was initially damaged by the strike which led to the failure of the exhaust valve which, in turn, internally destroyed the piston, which explains the broken case halves. There has been no FAA inquiry into the incident.

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Original NASA ASRS Text

Title: INFLT ENGINE SHUTDOWN WHEN STARBOARD ENGINE FAILS 19 MINUTES AFTER LIGHTNING STRIKE.

Narrative: AN INSTRUMENT FLT PLAN WAS FILED FROM CMX TO 8D4 IN A TWIN SMT. WHEN MY PAX ARRIVED, THEY SAID THEY WANTED TO MAKE AN INTERMEDIATE STOP AT IRON MOUNTAIN, MI. ANOTHER WX BRIEFING WAS RECEIVED JUST PRIOR TO DEP, BUT IT INDICATED THIS STOP WAS NOT POSSIBLE DUE TO TSTMS IN THAT AREA. THE ORIGINAL FLT PLAN WAS USED, ALLOWING FOR A DEVIATION TO THE E TO AVOID HEAVY WX. AFTER TKOF, CENTER SAID THAT MOST ACFT IN THE AREA WERE DIVERTING E, AND THAT I COULD DO SO TOO, IF I DESIRED. THAT INFO AGREED WITH THE BRIEFING EARLIER, SO THAT IS WHAT I DID. ONBOARD WX RADAR WAS USED FOR TSTM AVOIDANCE. EVEN SO, IT WAS A ROUGH RIDE, AND I FREQUENTLY SLOWED THE ACFT TO MANEUVERING SPD. I SAW LIGHTNING CLOSE BY ONCE, BUT I DIDN'T KNOW THE ACFT WAS STRUCK UNTIL THE POST-FLT INSPECTION. ALL AVIONICS CONTINUED TO WORK NORMALLY. ABOUT 10 MINS LATER, NOW IN VMC, THE RIGHT ENG FAILED. THE ENG WAS FEATHERED, THE CHKLIST PERFORMED AND ATC NOTIFIED. THROUGH THE CENTER CTLR MY COMPANY WAS PHONED AND ADVISED OF THE EXISTING MECHANICAL FAILURE. POS AT THE TIME OF FAILURE WAS 59 DME N OF WHITE CLOUD VOR, ALT 13000' AT 64% PWR. RUNUP AT CMX WAS NORMAL AS WERE ALL ENG GAUGES. THE FLT WAS CONTINUED TO THE DEST W/O FURTHER INCIDENT. THE IFR FLT PLAN WAS CLOSED 3 MI N OF THE ARPT, WITH AN UNEVENTFUL APCH AND LNDG. POST-FLT INSPECTION OF THE ACFT REVEALED EXTERNAL DAMAGE TO THE ENG. THERE IS A HOLE ON TOP OF THE ENG WHERE BOTH CASE HALVES ARE BROKEN. PIECES OF PISTON WERE FOUND IN THE ENG COMPARTMENT. LIGHTNING DAMAGE IS A SMALL HOLE IN THE RADOME, SMALL HOLES IN BOTH FIBERGLASS LEADING EDGE FAIRING ADJACENT TO THE FUSELAGE, AND A BURNED AREA IN THE TOP TRNING EDGE OF THE RUDDER WHERE THE LIGHTNING APPARENTLY EXITED. THE OPINION EXPRESSED BY THE DIRECTOR OF MAINT AND THE INSPECTOR FROM THE INSURANCE COMPANY IS THAT LIGHTNING CAUSED DAMAGE RESULTING IN AN ENG FAILURE A SHORT TIME AFTER THE STRIKE. THE INSURANCE COMPANY SAID OUR CLAIM WAS THE FIFTH ACFT LIGHTNING STRIKE CLAIM MADE TO THEM CONCERNING ACFT LIGHTNING STRIKES IN THAT WX SYS THAT DAY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR STATED THAT HE WAS ABOUT 5 MI FROM THE CELLS ON THE RADAR, UTILIZING AN X BAND RADAR SET. POST-FLT INSPECTION REVEALED THE DAMAGE AND MAINT FOUND THAT BOTH ENGS WERE MAGNETIZED BY THE LIGHTNING STRIKE. AN ANALYSIS OF THE PARTS LED TO A THEORY THAT THE VALVE GUIDE WAS INITIALLY DAMAGED BY THE STRIKE WHICH LED TO THE FAILURE OF THE EXHAUST VALVE WHICH, IN TURN, INTERNALLY DESTROYED THE PISTON, WHICH EXPLAINS THE BROKEN CASE HALVES. THERE HAS BEEN NO FAA INQUIRY INTO THE INCIDENT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.