Grumman Acft Eng Cor-Schweizer G-164B N6607Q accident near Buckeye, Arizona

Probable cause

An increase in engine rpm and vibration, which resulted in an aborted takeoff and runway excursion. The reason for the increased engine rpm and vibration could not be determined because of postaccident fire damage.

NTSB analysis

The pilot had flown the airplane about 4.2 hours on the date of the accident with no discrepancies noted. During the accident takeoff, the pilot noted normal acceleration, engine indications, and tail liftoff. After completing 2/3 of the takeoff roll, the engine rpm increased to 2,600-2,700 (the maximum allowable is 2,550 rpm). The pilot felt a moderate-to-severe vibration and immediately initiated procedures for an aborted takeoff. He retarded the throttle to idle, applied maximum braking, and held the control stick full aft. As the airplane slowed to 20-30 knots, he steered the airplane away from a fence at the end of the runway onto hard packed desert terrain. After rolling a short distance, the left main landing gear encountered a depression in the terrain and sheared off. The airplane settled onto the left wing and was almost immediately engulfed in fire. Fire consumed the cabin and inboard wing areas, as well as the aft section of the engine, which exposed the gears in the accessory section. Fire consumed all accessories, including both magnetos. A postaccident examination of the engine could not determine a reason for the increase in rpm and vibration due to fire damage.

Text from the NTSB. Open the NTSB docket for WPR10LA413 for the full record.