NTSB Identification: LAX05LA186.
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Accident occurred Sunday, May 22, 2005 in Santa Barbara, CA
Probable Cause Approval Date: 04/25/2006
Aircraft: Classic Aircraft Corp Waco YMF-5, registration: N181AS
Injuries: 3 Minor.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The airplane collided with the ground while attempting a return to runway maneuver following a loss of engine power in the takeoff initial climb. The airplane came to rest in a slough next to the runway. A post accident examination of the airplane and engine was conducted by National Transportation Safety Board investigators. Examination of the magnetos found that the points gap on the right magneto was 0.026 inches and 0.036 inches on the left (the Jacobs R755 A2/B2 Operator's Manual specifies a points gap of 0.010 to 0.014 inches). The right magneto showed signs of points contact burning and of heating due to a lack of periodic oiling. Both magnetos were missing the spring-loaded oil cup at the base of the magneto. Magneto timing to the engine was checked and found to be 36 degrees before Top Dead Center (BTDC) for the right magneto and 27 degrees BTDC for the left magneto (the operator's manual specifies 31 degrees BTDC for both magnetos. Both magnetos were then removed from the engine for a bench check. Both magnetos threw sparks from the rotating cylinder to the housing, but the right magneto sparked excessively (arcing), indicating a possible failed condenser. The left magneto had a strong spark, whereas the right magneto displayed a weak coil, failing as it got warm. During the removal of the spark plugs, it was found that the number 5 spark plug was only finger tight with evidence of exhaust blow-by at the spark plug gasket area. According to a carburetor icing probability chart, at the time of the accident the ambient temperature and dew point were conducive to "Serious Icing at Glide Power." The pilot was on the ground holding at idle for about 15 minutes prior to being given a clearance for takeoff.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: a loss of engine power due to carburetor ice aggravated by the poor operating condition of the magnetos and the improper magneto-to-engine timing. Full narrative available
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