Accident Grumman G-164A AgCat RP-R4456, Monday 21 August 2023

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Date:	Monday 21 August 2023
Time:	07:30
Type:	Grumman G-164A AgCat
Owner/operator:	South Pacific Aerial Spraying Services (SPASS)
Registration:	RP-R4456
MSN:
Fatalities:	Fatalities: 0 / Occupants: 1
Other fatalities:	0
Aircraft damage:	Substantial
Category:	Accident
Location:	Lambayong Airstrip, Sultan Kudarat, Maguindanao - Philippines
Phase:	Initial climb
Nature:	Agricultural
Departure airport:
Destination airport:
Investigating agency:	AAIB Philippines
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
An Ag Cat G-164A, RP-R4456, sustained substantial damage following loss of engine power upon take-off at Lambayong Airstrip. The sole occupant sustained minor injury.
It was during the initial climb of the fifth (5th) load of chemicals for the swathing operation that the aircraft experienced engine vibration. A decrease in engine rpm ensued, leading to the eventual loss of engine power. The pilot was not able to dump the load of chemicals before the aircraft made a forced landing in an open area. The aircraft initially touched down on its main gears and swerved to the left as it continued to roll. It came to a complete stop in an inverted position after both wings collided with two gimelina trees.

Primary Cause
a. Failure of the number three (3) cylinder, resulting in a total loss of engine power.
Contributory Cause
a. Non-adherence to the specific temperature limitation of the R-985 engine.
b. Non-inclusion in the pre- and post-flight visual inspection of the cylinder head cooling fins for discoloration or casting marks as an indication that a crack was developing.

Accident investigation: