ASN Wikibase Occurrence # 286272
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| Date: | Tuesday 26 February 2008 |
| Time: | 16:45 LT |
| Type: |  Beechcraft A36 |
| Owner/operator: | Private |
| Registration: | N623CQ |
| MSN: | E-1382 |
| Year of manufacture: | 1978 |
| Total airframe hrs: | 1061 hours |
| Engine model: | Continental IO 520 SERIES |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Athens, Georgia -
 United States of America
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | Lawrenceville-Gwinnett County Briscoe Field, GA (LZU/KLZU) |
| Charlotte-Douglas Airport, NC (CLT/KCLT) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
After takeoff on the first flight following a propeller overhaul, the airplane was leveled at 7,000 feet, and as the pilot and pilot-rated passenger discussed engine management, they noted the propeller rpm was high. They diverted to an alternate destination, and notified air traffic control (ATC). The propeller was adjusted but continued to overspeed. The pilot rated passenger managed engine and propeller rpm while the pilot flew the airplane at the manufacturer's best glide speed of 110 knots, but the engine continued to overspeed as the propeller provided no thrust. As propeller thrust and altitude decayed, the airplane descended through a cloud layer. When the airplane broke out beneath the cloud layer, the pilot selected a field for a forced landing area due to the fact that the surrounding terrain was wooded. Upon touchdown, the airplane bounced, the nose gear collapsed, and the airplane skidded to a stop. The pilot and pilot rated passenger stated that prior to the accident flight an annual inspection was completed and a newly overhauled propeller was installed. Disassembly of the propeller system after the accident revealed the rear pitch change rod bushing separated from the rear hub half and became loose in the hub. The bushing displayed traces of bonding sealant; however, the hub bore for the bushing did not. The hub cavity and the area on the aft side of the propeller piston, which are normally dry, contained "significant" amounts of oil. Pressurized oil on both sides of the propeller piston resulted in a hydraulic lock, fixed pitch condition. Using the as-found condition of the accident propeller system, engineers determined that airspeed of 97 knots or slower would be required to create positive thrust from the propeller system. After the accident, the propeller manufacturer revised its inspection and repair criteria, and changed the pitch change rod bushing installation procedure from one that used bonding sealants, to one that required a spiral retaining ring. The use of bonding sealants was no longer permitted.
Probable Cause: The loss of propeller thrust due to the unseating of an internal propeller hub bushing. Contributing to the accident was the manufacturer's inadequate procedure to secure the bushing.
Accident investigation:
 |
|
Sources:
NTSB NYC08LA112
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 03-Oct-2022 08:15 | ASN Update Bot | Added |
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