NTSB Identification: LAX90FA145.
The docket is stored on NTSB microfiche number 43463.
Nonscheduled 14 CFR
Accident occurred Friday, April 13, 1990 in GRAND CANYON, AZ
Probable Cause Approval Date: 04/13/1992
Aircraft: CESSNA T207, registration: N91081
Injuries: 7 Serious.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

ACCORDING TO WITNESSES, THE ACFT WAS ABOUT TO TOUCHDOWN FROM A NORMAL APCH TO RWY 21, WHEN IT ENCOUNTERED VARIALBLE WIND CONDS & BALLOONED TO ABOUT 70' AGL. THE PLT INITIATED A GO-AROUND. SHORTLY THEREAFTER, WITNESSES OBSERVED A PUFF OF SMOKE EMANATE FROM THE ACFT, THEN THE PLT TRANSMITTED THAT THE FLT WAS 'GOING DOWN.' SUBSEQUENTLY, THE ACFT COLLIDED WITH TREES ON WOODED TERRAIN ABOUT 1/2 MI FROM THE DEP END OF THE RWY. AN EXAM REVEALED A LACK OF POWER SIGNATURES ON THE PROP; EVIDENCE OF SOOTING WAS FOUND ON THE SPARK PLUGS (INDICATING A RICH MIXTURE). TESTING OF THE TURBO-CONTROLLER REVEALED EVIDENCE THAT IT HAD BEEN ADJUSTED TO A LOW SETTING; THE TURBO WOULD ONLY PRODUCE A MAXIMUM AIR FLOW EQUAL TO HIGH CRUISE POWER. THE ENG MANUFACTURER RPRTD THAT THIS SITUATION COULD PRODUCE AN OVER-RICH MIXTURE, PARTICULARILY IF THE THROTTLE AND/OR MIXTURE CONTROLS WERE IMPROPPERLY MANIPULATED. THE PILOT LACKED EXPERIENCE IN ACFT WITH TURBO-CHARGED ENGS & HE WAS NOT TRAINED IAW THE COMPANY TRAINING PROGRAM.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

IMPROPER ADJUSTMENT OF THE TURBO-CHARGER ABSOLUTE PRESSURE CONTROLLER, AND IMPROPER MANIPULATION OF THE POWER PLANT CONTROLS BY THE PILOT DURING THE GO-AROUND. FACTORS RELATED TO THE ACCIDENT WERE: FAILURE OF COMPANY MANAGEMENT TO PROPERLY TRAIN THE PILOT IN ACCORDANCE WITH THE APPROVED COMPANY TRAINING PROGRAM, AND THE PILOT'S LACK OF EXPERIENCE IN TURBO-CHARGED ENGINE OPERATIONS.

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