Accident Zenith CH601 N239PC,
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ASN Wikibase Occurrence # 284597
 
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Date:Saturday 14 July 2007
Time:10:30 LT
Type:Silhouette image of generic CH60 model; specific model in this crash may look slightly different    
Zenith CH601
Owner/operator:
Registration: N239PC
MSN: 6-4235
Total airframe hrs:3 hours
Engine model:Rotax 912 UL
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Rosamond, California -   United States of America
Phase: Unknown
Nature:Private
Departure airport:Rosamond, CA (L00)
Destination airport:Rosamond, CA (L00)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The accident flight was the airplane's maiden flight where the pilot was to complete a series of shallow banks. After doing the predetermined maneuvers, which included four simulated approaches to landing, he descended to traffic pattern altitude. As he maneuvered onto the base leg, he reduced the engine power from about 4,500 rpm to 2,000 rpm. The airplane began to lose a significant amount of altitude, and in response, the pilot moved the throttle control forward. The engine then had a total loss of power. The airplane descended and impacted the roof of a private residence. Examination of the airplane and engine following the accident revealed the upper spark plugs were all a similar black coloration, indicating that the fuel/air mixture was rich. Additional evidence of a rich mixture was found with dark black residue lining the tail pipe exhaust. After starting the engine during a postaccident examination, the throttle control was manipulated and the engine responded appropriately. The engine emitted a thick white smoke during operation. Investigators noted that when retarding the throttle toward the idle position, the throttle arms did not move against the idle adjustment screw stops. Manual manipulation of both throttle arms to the carburetors' adjustment screws resulted in a loss of power. The same action was repeated four times, producing the same results. The right carburetor bowl contained a brown colored liquid similar in color to a maple syrup; the odor was consistent with a varnished fuel. The left carburetor bowl contained a small amount of fluid that was similar to that of the fluid found in the right carburetor, though a shade lighter in color. The fuel found in the center fuel tank was also varnished. In the 7 months prior to the accident, the engine had only been run on 11 occasions, all on the ground, for a total of 2 hours of operational time.

Probable Cause: A total loss of engine power during approach due to the improper idle screw/stop adjustment. A factor contributing to the accident was deteriorated fuel.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: LAX07LA218
Status: Investigation completed
Duration: 8 months
Download report: Final report

Sources:

NTSB LAX07LA218

Revision history:

Date/timeContributorUpdates
30-Sep-2022 19:07 ASN Update Bot Added

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