NTSB Identification:
FTW99LA027 .
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Accident occurred Monday, November 16, 1998 in SAN ANGELO, TX
Probable Cause Approval Date: 9/28/1999
Aircraft: Mooney M20J, registration: N201QK
Injuries: 1 Minor.
The airplane was en route cruising at 9,500 feet msl approximately 12 miles east of its destination, when the pilot reported a loss of engine power. At 2,200 feet msl, the pilot reported that he would not make the runway. During the off airport landing, the airplane struck a tree, the right wing separated from the airframe, the airplane descended into the water, and came to rest inverted in water 7 feet deep. Examination of the wreckage revealed engine oil in the single drive dual magneto and one of the rear case bearing retaining plate screws was broken. The magneto was removed from the engine and disassembled. A metallurgist found that screw failure was a result of delayed fracture from hydrogen embrittlement and the 'hydrogen was most likely picked up during the cadmium plating for corrosion resistance at original manufacture of the screw.' The magneto had accumulated 775.58 hours since last overhaul in 1993. At the last annual inspection, November 1998, the magneto points and timing were checked. Time since that annual inspection was 3.27 hours. Service Bulletin (SB) 643 dated 02/08/94 recommended magnetos be 'overhauled or replaced at the expiration of four years without regard to the accumulated operating hours since new or last overhaul.' No evidence was found that the SB had been accomplished; however, under 14 CFR Part 91 operations, compliance with the SB is not required. The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The total loss of engine power due to the magneto failure resulting from oil contamination when the bearing plate retainer screw fractured due to improper manufacturing. Factors were the lack of suitable terrain for the forced landing, and the dark night conditions.
NTSB Identification:
NYC04LA192.
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Accident occurred Saturday, August 14, 2004 in Rhinebeck, NY
Probable Cause Approval Date: 9/13/2005
Aircraft: Waco QCF, registration: N11478
Injuries: 1 Uninjured.
During the initial climb after takeoff, the airplane experienced a partial loss of engine power, and the pilot elected to perform a forced landing to the grass at the runway overrun. During the landing, the airplane's lower left wing, propeller and left wing were damaged. The pilot reported that the airplane was fueled, and then flew normally for about 25 minutes earlier on the day of the accident. On scene examination of the engine, which included an inspection of intake, exhaust, and fuel system, did not reveal any pre-impact malfunctions. A subsequent teardown of the engine did not reveal any catastrophic failures; however, a mechanic reported that bench testing of the magnetos revealed that they both contained open secondary windings. During an interview, the mechanic further stated that the problem with the magnetos was not apparent until they were heated to a temperature of about 130 degrees. The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
A partial loss of engine power due to a magneto failure.
NTSB Identification:
ATL97LA009 .
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Accident occurred Friday, October 25, 1996 in AMELIA ISLAND, FL
Probable Cause Approval Date: 8/21/1997
Aircraft: Mooney M20K, registration: N32DG
Injuries: 2 Serious, 1 Minor, 1 Uninjured.
During the climb after takeoff, the engine began to run rough, then lost power. According to the pilot, he turned on the boost pump, and the engine quit. The pump was turned off, the engine surged, then quit again. During a forced landing, the airplane struck trees, then came to rest on a street. Postaccident examination of the engine revealed corrosion in the left magneto, which was indicative of moisture contamination of the magneto that may have resulted in a loss of power. Additionally, the engine driven fuel pump pressure was set high, which would have resulted in a rich mixture, when the boost pump was activated. The engine had been equipped with pressure type, Slick Electro Model 6224 magnetos. A service bulletin, applicable to another aircraft manufacturer, had been issued by the magneto manufacturer to inspect the pressurized magnetos each 100 hours for evidence of moisture contamination. The same information was contained in the magneto maintenance and overhaul manual. The airplane was maintained under an annual inspection program, with no intervening 100 hour inspections; 159 hours of flight time had been accumulated since the last annual inspection. The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
inadequate maintenance/inspection, which resulted in a failure to detect and correct moisture contamination of the left magneto; and/or improper adjustment of the engine fuel pump output, which resulted in excessive fuel pressure.
NTSB Identification:
ATL96LA128 .
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Accident occurred Thursday, September 19, 1996 in GEORGETOWN, SC
Probable Cause Approval Date: 7/28/1997
Aircraft: Piper PA-32-300, registration: N9VM
Injuries: 1 Minor.
While climbing through about 2,500 feet after takeoff, the engine lost power. The pilot was forced to land on unsuitable terrain, which resulted in a collision with a tree. After the accident, the engine's left magneto was found jammed due to a failed impulse coupling. The jammed magneto broke the idler gear and the crankshaft gear with which it meshed, precipitating a total loss of power. The impulse coupling was the subject of an airworthiness directive that required recurring inspections at each 500 hours of engine operation. Records showed that the last inspection of the magneto was in November 1988, 432 hours after the engine had been overhauled. The last annual inspection was in October 1995, with a tachometer time of 2,905 hours since overhaul. At the time of the accident, the engine had a total flight time of 3,109 hours recorded since overhaul. The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
failure of maintenance personnel to comply with an airworthiness directive, requiring periodic magneto inspections; inadequate annual inspection of the airplane by (other) maintenance personnel; and subsequent failure of the impulse coupling in the left magneto, which resulted in a jammed magneto, failure of the idler and crankshaft gears, and subsequent loss of engine power. The lack of suitable terrain for a forced landing was a related factor.
NTSB Identification:
CHI93DTG03 .
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Accident occurred Friday, August 20, 1993 in WASHBURN, ND
Probable Cause Approval Date: 8/17/1994
Aircraft: PIPER PA-25-235, registration: N4693Y
Injuries: 1 Uninjured.
The pilot was maneuvering to make a spray run on an aerial application flight when the airplane lost all engine power. The pilot made a forced landing in the field, and struck two fence posts during landing roll. The engine examination revealed the impulse coupling flyweight in the left magneto had jammed and seized the magneto. The magneto drive gear and the camshaft gear were stripped. The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
the loss of engine power due to a magneto failure.
