ASN Wikibase Occurrence # 176498
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| Date: | Tuesday 20 April 2004 |
| Time: | 18:35 |
| Type: |  Piper PA-23-250 Aztec |
| Owner/operator: | Private |
| Registration: | N6257H |
| MSN: | 277654057 |
| Total airframe hrs: | 4000 hours |
| Engine model: | Lycoming IO-540-C4B5 |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Sweetwater, TX -
 United States of America
|
| Phase: | Landing |
| Nature: | Ferry/positioning |
| Departure airport: | Midland, TX (MAF) |
| Sallisaw, OK (JSV) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The propeller on the number two engine on a light twin-engine airplane experienced an overspeed while in cruise flight. The 1,430-hour pilot reported that while in cruise flight at 5,500 feet msl, he noticed the propellers were "out of sync." The pilot stated that he made minor adjustments with the propeller levers to synchronize the propellers; however, the propellers continued to be "out of sync." The right propeller began to overspeed by approximately 1,000 RPM's, and adjustments with the right prop lever had no effect. The pilot retarded the throttle, but could not maintain proper engine RPM, so he elected to land at the nearest airport, located approximately 12 miles away. The pilot noticed that the number two engine was starting to overheat, so he retarded the throttle again and increased airspeed to aid in cooling. The airplane started to shake, and he looked outside and observed the propeller was "wobbling." Subsequently, the pilot executed a forced landing into a muddy wheat field. The airplane had an annual inspection on December 12, 2003, and was determined to be in an un-airworthy condition. The airplane was given a special flight permit for maintenance, issued on April 20, 2004, which was to expire on April 30, 2004. The propeller governors were tested on a governor test stand and functioned normally; however, they were out of specification. The maximum RPM on the left governor was 2,394 and the maximum RPM on the right governor was 2,310. The specified RPM is 2,435. The specified feather RPM is 1,700. The left governor achieved 1,671 RPMs and the right governor achieved 1,634 RPMs. Inspection after disassembly was uneventful. Both governors were found to be "old and worn, exhibited similar wear patterns, but were functional." The reason for the reported propeller overspeed could not be determined.
Probable Cause: The propeller overspeed for undetermined reasons. A contributing factor was the lack of suitable terrain for the forced landing.
Accident investigation:
 |
|
Sources:
NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20040428X00522&key=1
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 30-May-2015 14:29 | Noro | Added |
| 21-Dec-2016 19:30 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 07-Dec-2017 17:53 | ASN Update Bot | Updated [Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative] |
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