Narrative:

While in IMC on an IFR flight plan and deviating south off course to avoid a build-up, our aircraft was apparently struck by lightning. When that occurred, we lost our autoplt, mach trim, primary stabilizer trim, flight director, and radar. We were in a block altitude (FL430-FL470) at FL435. We began a descent to the bottom of our block (FL430) and requested a descent to FL410 (per the checklist procedure). As we were accomplishing the checklist for loss of stabilizer trim, we may have descended below our assigned altitude. Once the checklist was complete, and we regained control of the stabilizer trim with our secondary trim system, we leveled the aircraft at FL430. Center cleared us to descend and fly direct to ict. We landed uneventfully at ict. Callback conversation with reporter revealed the following information: the reporter stated the aircraft was struck by lightning and failed the autoplt, mach trim, primary stabilizer trim, yaw dampers, both flight directors and the WX radar. The reporter said no emergency was declared, but a diversion was made to ict. The reporter stated the secondary pitch trim was switched on and functioned normally, but an altitude deviation was incurred during the event. The reporter said, on the ground, in addition to the electronic units that were replaced, burn spots were discovered on the horizontal stabilizer. The reporter, when questioned by the analyst of the condition of the static dischargers, stated they were found not damaged. Supplemental information from acn 624500: we were getting light-moderate turbulence and the vsi showed -800 ft to +400 ft. We were in 'altitude hold' mode for the autoplt. The radar was set in autotilt (+1.5 degrees), set in 50 NM range, and was showing scattered level 1 activity. We were at least 40 NM from the magenta activity. Within about 3 mins we saw approximately 5 lightning bolts in IMC. The PIC began hand flying the aircraft using 'raw data' and called for the 'primary stabilizer trim fail' checklist. It directed us to slow to .82 mach and descend to FL410. I saw we were just above FL427, according to my instruments. Center made us aware of our altitude. We climbed back to FL430. During our subsequent descent I switched my instruments to air data computer #1 to eliminate the altitude difference. Under no circumstances should a PF who is hand flying ever manipulate the FMS. But, it is hard to resist when everyone is busy. We should have operated the radar in and out of autotilt so we could see the cells below us.

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Original NASA ASRS Text

Title: A C750 IN CRUISE AT FL430 IN ZDV'S AIRSPACE WAS STRUCK BY LIGHTNING AND DIVERTED TO ICT DUE TO FAILURE OF THE MACH TRIM, AUTOPLT, PRIMARY STABILIZER TRIM, L AND R FLT DIRECTORS, YAW DAMPERS AND WX RADAR.

Narrative: WHILE IN IMC ON AN IFR FLT PLAN AND DEVIATING S OFF COURSE TO AVOID A BUILD-UP, OUR ACFT WAS APPARENTLY STRUCK BY LIGHTNING. WHEN THAT OCCURRED, WE LOST OUR AUTOPLT, MACH TRIM, PRIMARY STABILIZER TRIM, FLT DIRECTOR, AND RADAR. WE WERE IN A BLOCK ALT (FL430-FL470) AT FL435. WE BEGAN A DSCNT TO THE BOTTOM OF OUR BLOCK (FL430) AND REQUESTED A DSCNT TO FL410 (PER THE CHKLIST PROC). AS WE WERE ACCOMPLISHING THE CHKLIST FOR LOSS OF STABILIZER TRIM, WE MAY HAVE DSNDED BELOW OUR ASSIGNED ALT. ONCE THE CHKLIST WAS COMPLETE, AND WE REGAINED CTL OF THE STABILIZER TRIM WITH OUR SECONDARY TRIM SYS, WE LEVELED THE ACFT AT FL430. CTR CLRED US TO DSND AND FLY DIRECT TO ICT. WE LANDED UNEVENTFULLY AT ICT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT WAS STRUCK BY LIGHTNING AND FAILED THE AUTOPLT, MACH TRIM, PRIMARY STABILIZER TRIM, YAW DAMPERS, BOTH FLT DIRECTORS AND THE WX RADAR. THE RPTR SAID NO EMER WAS DECLARED, BUT A DIVERSION WAS MADE TO ICT. THE RPTR STATED THE SECONDARY PITCH TRIM WAS SWITCHED ON AND FUNCTIONED NORMALLY, BUT AN ALTDEV WAS INCURRED DURING THE EVENT. THE RPTR SAID, ON THE GND, IN ADDITION TO THE ELECTRONIC UNITS THAT WERE REPLACED, BURN SPOTS WERE DISCOVERED ON THE HORIZ STABILIZER. THE RPTR, WHEN QUESTIONED BY THE ANALYST OF THE CONDITION OF THE STATIC DISCHARGERS, STATED THEY WERE FOUND NOT DAMAGED. SUPPLEMENTAL INFO FROM ACN 624500: WE WERE GETTING LIGHT-MODERATE TURB AND THE VSI SHOWED -800 FT TO +400 FT. WE WERE IN 'ALT HOLD' MODE FOR THE AUTOPLT. THE RADAR WAS SET IN AUTOTILT (+1.5 DEGS), SET IN 50 NM RANGE, AND WAS SHOWING SCATTERED LEVEL 1 ACTIVITY. WE WERE AT LEAST 40 NM FROM THE MAGENTA ACTIVITY. WITHIN ABOUT 3 MINS WE SAW APPROX 5 LIGHTNING BOLTS IN IMC. THE PIC BEGAN HAND FLYING THE ACFT USING 'RAW DATA' AND CALLED FOR THE 'PRIMARY STABILIZER TRIM FAIL' CHKLIST. IT DIRECTED US TO SLOW TO .82 MACH AND DSND TO FL410. I SAW WE WERE JUST ABOVE FL427, ACCORDING TO MY INSTS. CTR MADE US AWARE OF OUR ALT. WE CLBED BACK TO FL430. DURING OUR SUBSEQUENT DSCNT I SWITCHED MY INSTS TO ADC #1 TO ELIMINATE THE ALT DIFFERENCE. UNDER NO CIRCUMSTANCES SHOULD A PF WHO IS HAND FLYING EVER MANIPULATE THE FMS. BUT, IT IS HARD TO RESIST WHEN EVERYONE IS BUSY. WE SHOULD HAVE OPERATED THE RADAR IN AND OUT OF AUTOTILT SO WE COULD SEE THE CELLS BELOW US.

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.