Accident Cessna 337G Super Skymaster N337LC,
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ASN Wikibase Occurrence # 139799
 
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Date:Thursday 10 November 2011
Time:16:15
Type:Silhouette image of generic C337 model; specific model in this crash may look slightly different    
Cessna 337G Super Skymaster
Owner/operator:Lamp Ministry Inc
Registration: N337LC
MSN: 33701672
Year of manufacture:1976
Total airframe hrs:4386 hours
Engine model:Continental IO-360 SER
Fatalities:Fatalities: 1 / Occupants: 1
Aircraft damage: Destroyed
Category:Accident
Location:2 miles S. of Alamosa, near San Luis Valley Regional Airport - KALS, C -   United States of America
Phase: Initial climb
Nature:Private
Departure airport:Alamosa, CO (ALS)
Destination airport:Salida, CO (ANK)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
One witness reported that the pilot started both engines before takeoff and that both the front and rear engines were running for about 5 minutes before he started to taxi the airplane. Another witness reported seeing the airplane flying just after takeoff at a low altitude and then hearing the engine shut off before the airplane went out of sight behind a stand of trees. Another witness reported seeing the airplane flying at a low altitude when it suddenly lost altitude and nose dived toward the ground.
The twin-engine airplane’s fuselage had two engines in tandem, one engine in front of the cabin and one engine behind the cabin. The airplane had retractable landing gear and a belly-attached cargo pod. Examinations of the rear engine’s propeller blade assembly showed evidence that it was not producing power at impact. The front engine’s propeller blade assembly showed evidence that it was producing power at impact. Examinations of the fuel distribution system revealed that the front engine fuel selector handle was set to the left tank. The front engine fuel selector valve was found between the “left tank” and “off” positions. The rear engine fuel selector handle and valve were found in the “off” position; therefore, the rear engine was most likely starved of available fuel, which is consistent with the physical and witness evidence of a loss of power to the rear engine. Further, given the witness statement that both engines were running before departure, it is likely that the fuel selector was inadvertently moved to the “off” position during, or shortly after, takeoff.
Detailed examinations of the airframe components and teardowns of both engines did not reveal any preexisting mechanical anomalies that would have contributed to the accident. The Pilot’s Operating Handbook (POH) noted that the airplane’s single-engine climb rate is reduced 15 feet per minute (fpm) with the belly cargo pod attached and 240 fpm when the gear is in transit. The actual weight of the airplane at the time of the accident could not be determined due to a lack of fuel and airplane empty weight information. A weight of 4,000 pounds, the lightest weight shown in the POH, was used for airplane performance calculations, which showed that, at the time of the accident, the airplane’s single-engine climb rate with the belly cargo pod attached was about 99 fpm. Given that the main landing gear were likely in transit, the climb rate could have been reduced by as much as 240 fpm. In this condition, the airplane would not have been able to climb and the pilot would not have been able to maintain level flight.

Probable Cause: The loss of power to the rear engine due to fuel starvation during takeoff, which resulted from the fuel selector valve being inadvertently moved to the “off” position, and resulted in the airplane’s inability to climb.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CEN12FA058
Status: Investigation completed
Duration: 2 years and 10 months
Download report: Final report

Sources:

NTSB

History of this aircraft

Other occurrences involving this aircraft
27 December 1995 N990LB Lutheran Missionaries 0 Stevens Village, AK sub
27 April 2001 C-GMBB Private 0 Red Lake, Ontario sub
19 February 2002 C-GMBB Lutheran Assn of Missionaries and Pilots 0 Red Lake, Ontario sub

Location

Revision history:

Date/timeContributorUpdates
11-Nov-2011 00:27 gerard57 Added
12-Nov-2011 03:51 RobertMB Updated [Time, Aircraft type, Registration, Cn, Operator, Other fatalities, Location, Phase, Departure airport, Destination airport, Source, Narrative]
27-Sep-2014 08:00 Aerossurance Updated [Time, Source, Narrative]
21-Dec-2016 19:26 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
27-Nov-2017 17:25 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]

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