Wirestrike Accident Cessna T337C Super Skymaster N2576S,
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ASN Wikibase Occurrence # 153248
 
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Date:Wednesday 13 February 2013
Time:13:14
Type:Silhouette image of generic C337 model; specific model in this crash may look slightly different    
Cessna T337C Super Skymaster
Owner/operator:Private
Registration: N2576S
MSN: 337-0876
Year of manufacture:1968
Total airframe hrs:1350 hours
Engine model:Continental TSIO-360-A
Fatalities:Fatalities: 1 / Occupants: 1
Aircraft damage: Destroyed
Category:Accident
Location:West of New Smyrna Beach Municipal Airport - KEVB, New Smyrna Beach, F -   United States of America
Phase: Take off
Nature:Private
Departure airport:New Smyrna Beach, FL (EVB)
Destination airport:New Smyrna Beach, FL (EVB)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
Shortly after taking off on the test flight, the pilot transmitted “mayday mayday” over the control tower’s radio frequency. According to eyewitnesses, the airplane was in a left-wing-down attitude when it impacted a tree, power lines, and then another tree before coming to rest in a pasture. A review of data downloaded from the engine data monitor revealed that the rear engine exhibited erratic fuel flow beginning 2 days before the accident and continuing through the accident flight. Further, the engine data monitor indicated that the rear engine’s propeller was under low-to-no power with a low pitch angle at the time of impact. The front engine exhibited no abnormalities or malfunctions, and the investigation found no other anomalies that would have precluded normal operation of the airplane.

During postaccident examination, the engine-driven fuel pump was removed and bench tested where it exhibited fuel flow higher than manufacturer guidelines with low fuel pressure. In order to meet bench test standards, an adjustment equal to three turns of the adjustment screw was made. The fuel pump then operated normally and was placed back on the engine; however, the engine still did not attain full power. Further examination revealed potential debris between the throttle assembly’s brass and stainless steel plates. After removal of the debris and reassembly of the throttle assembly, it operated within the normal range. Although the source of the debris could not be definitively determined, it likely originated in either in the fuel or a fuel tank.

Maintenance records indicate that two days before the accident, the fuel pump was removed, repaired, and reinstalled after work was completed on the rear fuel selector valve. After the pump was reinstalled, the mechanic adjusted the continuous flow fuel injection system using the airplane’s JPI engine monitor system and an external low pressure gauge to set the takeoff fuel flow; he then refueled the plane from containers in which he had stored the fuel in order to service the fuel pump. The following day, the pilot and the mechanic again adjusted the fuel pump’s fuel flow after conducting an unsatisfactory engine run-up . After the adjustment, the run-up appeared to be normal. Directives from the engine’s manufacturer recommended using a Model 20 ATM-C Porta Test Unit or equivalent to ensure the fuel injection system meets all pressure and flow specifications. Using a JPI engine monitor and an external gauge would have given inaccurate results without a properly calibrated fuel pump, and the mechanic’s recalibration of the engine-driven fuel pump’s adjustment screw would have only masked the debris issue within the throttle assembly.
Further, review of the manufacturer’s approved engine-out emergency procedures indicated that with a rear engine failure, the propeller should be immediately feathered and the landing gear retracted after obstacle clearance. Therefore, even with a loss of rear engine power, the airplane’s operating manual indicated that the airplane would have been able to climb at least 275 feet per minute with one engine, assuming the required pilot inputs were made. Had those single-engine climb performance conditions been met, the airplane likely would have been able to, at a minimum, maintain altitude until a safe landing could have been accomplished. However, as the rear propeller was found with a low pitch angle and the landing gear was found in the down and locked position after the accident, the airplane had not been configured for maximum single-engine performance as outlined in the engine-out procedures.

Probable Cause: Maintenance personnel's failure to follow procedures and published directives in calibrating the continuous flow fuel system and failure to accurately diagnose debris in the throttle assembly, resulting in a loss of power in one engine. Contributing to the accident was the pilot's failure to comply with published engine out procedures, which resulted in an off-airport landing and subsequent impact with a tree and the ground.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ERA13FA131
Status: Investigation completed
Duration:
Download report: Final report

Sources:

NTSB

Location

Revision history:

Date/timeContributorUpdates
13-Feb-2013 13:14 gerard57 Added
13-Feb-2013 16:34 Geno Updated [Aircraft type, Registration, Cn, Operator, Location, Departure airport, Source, Narrative]
14-Feb-2013 04:04 RobertMB Updated [Time, Aircraft type, Operator, Source, Narrative]
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
28-Nov-2017 14:09 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]

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