Accident Cessna 421C N6234G,
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ASN Wikibase Occurrence # 34604
 
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Date:Saturday 2 September 1995
Time:08:38 LT
Type:Silhouette image of generic C421 model; specific model in this crash may look slightly different    
Cessna 421C
Owner/operator:Adventure Airlines L.l.c.
Registration: N6234G
MSN: 421C0265
Year of manufacture:1977
Total airframe hrs:5461 hours
Engine model:CONTINENTAL GTSIO-520-L
Fatalities:Fatalities: 8 / Occupants: 8
Aircraft damage: Destroyed
Category:Accident
Location:Beaver Dam, AZ -   United States of America
Phase: En route
Nature:Executive
Departure airport:Las Vegas, NV (KVGT)
Destination airport:W. Yellowstone, MT
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
After climbing to 18,400' msl, the pilot reported a turbocharger problem & reversed course. He said he 'may lose the left engine' & that he was unable to maintain altitude. He diverted to an alternate airport. During a right turn onto final approach, the airplane was observed to cross (overshoot) the extended centerline of the runway. It continued in a right turn back toward the centerline, and then entered a left turn to intercept the inbound course. The turn steepened, and then the airplane entered a spin & crashed 1/2 mile short of the runway. A warped flange & evidence of exhaust gas leakage were found on the Inconel exhaust system Wye collector, at the wastegate outlet of the left engine. Neither propeller was in a feather position. There was evidence that the left engine was providing low power during impact. A note on the pilot's clipboard indicated that the (left engine) fuel flow & cylinder head temperature went to zero, & the manifold pressure dropped to 10 inches. The note also indicated that the pilot switched the 'boost pump' to high, the fuel flow went to 260 psi, & manifold pressure increased to 18.5 inches. Calculations showed that the airplane's gross weight (GW) & center-of-gravity (CG) were 7,645 pounds & 158.32 inches. The maximum allowable GW & CG were 7,450 pounds & 158 inches. During impact, the flaps were fully extended. The 'Engine Inoperative Landing' procedure stated, 'Wing Flaps - DOWN when landing is assured.' Most of the pilot's flight time in the Cessna 421 was before 1985; no record was found of recurrent training in the airplane since 1984. Annual and turbocharger inspections were made at 78 and 120 flight hours, respectively, before the accident, but no logbook entries were made concerning maintenance or replacement parts for the exhaust system.

Probable Cause: Failure of the pilot to maintain adequate airspeed, while maneuvering on approach, which resulted in an inadvertent stall/spin and uncontrolled collision with terrain. Factors relating to the accident were: the pilot allowed the aircraft weight and balance limitations to be exceeded; the pilot's lack of recurrent training in the make and model of airplane; inadequate maintenance/inspection of the engine exhaust systems; a warped and leaking exhaust system flange on the left engine, which resulted in a loss of power in that engine; and the pilot's improper use of the flaps.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: LAX95FA319
Status: Investigation completed
Duration: 9 months
Download report: Final report

Sources:

NTSB LAX95FA319

Location

Revision history:

Date/timeContributorUpdates
24-Oct-2008 10:30 ASN archive Added
09-Apr-2024 12:24 ASN Update Bot Updated [Time, Operator, Other fatalities, Phase, Departure airport, Destination airport, Source, Narrative, Category, Accident report]

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