|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||0601 To 1200|
|Locale Reference||atc facility : mer|
|Altitude||msl bound lower : 8000|
msl bound upper : 8000
|Operator||general aviation : corporate|
|Make Model Name||Small Transport, Low Wing, 2 Recip Eng|
|Flight Phase||cruise other|
|Route In Use||enroute airway : mer|
|Function||flight crew : single pilot|
|Qualification||pilot : private|
pilot : instrument
|Experience||flight time last 90 days : 301|
flight time total : 650
flight time type : 175
|Affiliation||government : military|
|Function||controller : approach|
|Qualification||controller : military|
|Anomaly||altitude deviation : excursion from assigned altitude|
non adherence : clearance
|Independent Detector||other flight crewa|
|Resolutory Action||flight crew : returned to intended course or assigned course|
flight crew : regained aircraft control
flight crew : overcame equipment problem
|Primary Problem||Flight Crew Human Performance|
|Air Traffic Incident||Pilot Deviation|
Engine failure was not just a total loss, but engine was surging and going from full power to no power in a cyclical pattern. Power was restored by turning auxiliary pumps to high, mixtures full rich, alternate air also was used. Airplane was extremely hard to control. In retrospect, it seems as if the autoplt was bucking and over controling trying to keep it straight and level when the turn coordinator was going crazy back and forth. I got it under control after autoplt was disengaged and engine began to run again. While this was all happening I lost about 300 or 400 ft of altitude. Mechanics can find no engine problem. I was under the freezing altitude level by a couple of degrees, so intake icing should not have been a problem. Temperature was +2 degrees C. I thought originally I might have lost the engine driven fuel pump, but it later turned out to be ok. Mixtures were leaned again later in the flight but auxiliary pumps were left on high until landing. More concentration on heading and altitude may have enabled me to keep from losing the altitude, but my primary concern was to regain control of the erratic airplane. One thing I thought about later that could help in the future would be an automatic autoplt disable if asymmetric thrust is detected. Maybe the pilot could have a guarded switch to allow the autoplt back on line after he has the engine feathered and the airplane retrimmed. I really think in this case anyway that the autoplt contributed to my confusion and I maybe could have handled the emergency without loss of altitude if I had immediately disengaged the autoplt. We did find after landing there had been a bird strike on that engine, but can't figure out how that could have caused this problem and think 8000 ft a bit high for birds. Must have got it on approach.
Original NASA ASRS Text
Title: 1 ENG SURGING AND AUTOPLT ERRATIC BEHAVIOR CAUSED PLT TO DESCEND OUT OF ASSIGNED ALT.
Narrative: ENG FAILURE WAS NOT JUST A TOTAL LOSS, BUT ENG WAS SURGING AND GOING FROM FULL PWR TO NO PWR IN A CYCLICAL PATTERN. PWR WAS RESTORED BY TURNING AUX PUMPS TO HIGH, MIXTURES FULL RICH, ALTERNATE AIR ALSO WAS USED. AIRPLANE WAS EXTREMELY HARD TO CONTROL. IN RETROSPECT, IT SEEMS AS IF THE AUTOPLT WAS BUCKING AND OVER CTLING TRYING TO KEEP IT STRAIGHT AND LEVEL WHEN THE TURN COORDINATOR WAS GOING CRAZY BACK AND FORTH. I GOT IT UNDER CONTROL AFTER AUTOPLT WAS DISENGAGED AND ENG BEGAN TO RUN AGAIN. WHILE THIS WAS ALL HAPPENING I LOST ABOUT 300 OR 400 FT OF ALT. MECHS CAN FIND NO ENG PROB. I WAS UNDER THE FREEZING ALT LEVEL BY A COUPLE OF DEGS, SO INTAKE ICING SHOULD NOT HAVE BEEN A PROB. TEMP WAS +2 DEGS C. I THOUGHT ORIGINALLY I MIGHT HAVE LOST THE ENG DRIVEN FUEL PUMP, BUT IT LATER TURNED OUT TO BE OK. MIXTURES WERE LEANED AGAIN LATER IN THE FLT BUT AUX PUMPS WERE LEFT ON HIGH UNTIL LNDG. MORE CONCENTRATION ON HDG AND ALT MAY HAVE ENABLED ME TO KEEP FROM LOSING THE ALT, BUT MY PRIMARY CONCERN WAS TO REGAIN CTL OF THE ERRATIC AIRPLANE. ONE THING I THOUGHT ABOUT LATER THAT COULD HELP IN THE FUTURE WOULD BE AN AUTOMATIC AUTOPLT DISABLE IF ASYMMETRIC THRUST IS DETECTED. MAYBE THE PLT COULD HAVE A GUARDED SWITCH TO ALLOW THE AUTOPLT BACK ON LINE AFTER HE HAS THE ENG FEATHERED AND THE AIRPLANE RETRIMMED. I REALLY THINK IN THIS CASE ANYWAY THAT THE AUTOPLT CONTRIBUTED TO MY CONFUSION AND I MAYBE COULD HAVE HANDLED THE EMER WITHOUT LOSS OF ALT IF I HAD IMMEDIATELY DISENGAGED THE AUTOPLT. WE DID FIND AFTER LNDG THERE HAD BEEN A BIRD STRIKE ON THAT ENG, BUT CAN'T FIGURE OUT HOW THAT COULD HAVE CAUSED THIS PROB AND THINK 8000 FT A BIT HIGH FOR BIRDS. MUST HAVE GOT IT ON APCH.
Data retrieved from NASA's ASRS site as of August 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.