Piper PA-24-180 N6597P

Summary

On 10 July 1999 at about 19:30 local time, a Piper PA-24-180 registered N6597P was involved in an accident near San Luis Obispo, California, 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

10 July 1999 at 19:30

Classification

Accident

Location

San Luis Obispo, California, United States

Nearest airport

San Luis Obispo (KSBP)

Coordinates

35.2510, -120.6202

Aircraft

Piper PA-24-180

Registration

N6597P

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Pacoima → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX99LA248

Nobody was injured.

The failure/separation of the crankshaft idler gear and the fatigue failure and subsequent separation of the crankshaft dowel pin due to the improper static and dynamic balance of the propeller by maintenance personnel.

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

Read the full NTSB narrative

The instructor said that the power came up smoothly on the takeoff roll, but that the engine suddenly quit at 600 feet agl. The flight instructor took the controls, lined up on a major interstate highway, and touched down in the northbound lanes. The right wing struck a bush, which spun the airplane off the highway and down the embankment next to the highway. An engine teardown disclosed that the crankshaft idler gear (left magneto) was detached from the mounting pad at the back of the crankcase. The crankshaft gear was not secured to the crankshaft, and the locating dowel pin was fractured and separated. Further examination of the idler gear shaft and attaching parts revealed severe wear signatures on the attachment bolts and locking plate, and the bolts displayed signatures consistent with prolonged contact with the rotating idler gear. The bore at the idler gear shaft-mounting pad was also severely worn and elongated. The crankshaft counterbore and corresponding gear revealed fretting and corrosion signatures at the mating surfaces, and the dowel pin was separated in line with the parting surfaces of the gear and counterbore. The dowel pin fracture surface displayed fatigue. A propeller overhaul was completed 20 hours prior to the accident. The Hartzell propeller manual prohibits balance weights in excess of 0.9 ounces (25.51 grams) in any one location on the spinner. Weights totaling 36 grams were found on one location on the airplane spinner.

Quoted verbatim from the NTSB record.