Beechcraft A36 N623CQ

Summary

On 26 February 2008 at about 21:45 local time, a Beechcraft A36 registered N623CQ, operated by C & S Aviation Inc, was involved in an accident near Athens, Georgia, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

26 February 2008 at 21:45

Classification

Accident

Location

Athens, Georgia, United States

Coordinates

33.9931, -83.1833

Aircraft

Beechcraft A36

Registration

N623CQ

Category

Airplane

Engines

1

Operator

C & S Aviation Inc

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Lawrenceville → Charlotte

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

NYC08LA112

Nobody was injured.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.