What happened
On the morning of March 04, 2014, a Piper PA 36-375 Pawnee Brave, registered as RP-R1420, was conducting agricultural spraying operations near the Farming Town Aerodrome (FADI) in Santo Tomas, Davao Del Norte. The aircraft, operated by Lapanday Food Corporation, was performing its second swathing sortie when the pilot noticed a sudden heat sensation within the cockpit.
Shortly after this sensation, smoke appeared beneath the rudder pedals, followed by orange flames emerging from the inspection holes on both sides of the cockpit floor. The pilot responded by climbing to an altitude of 3 and dumping the remaining chemical payload. After establishing a left downwind pattern for Runway 36, the pilot executed an emergency landing. The aircraft touched down approximately 250 feet from the runway threshold. The pilot successfully shut down the engine and fuel supply, allowing for a safe disembarkation without injury.
While the pilot escaped unharmed, the fire spread through the cockpit and fuselage. Emergency responders at the aerodrome extinguished the flames, but the aircraft suffered extensive damage. The fire destroyed the fuselage from the cockpit through to the empennage, melted the center wing box causing the wings to droop, and rendered the main landing gear unserviceable. The cockpit panel and agricultural equipment were also lost to the fire.
The investigation
An investigation by the AAIIB focused on the origin of the fire and the electrical conditions within the cockpit. Investigators examined the installation of supplemental avionics and the maintenance protocols of the operator. The inquiry established that the fire originated from an electrical malfunction related to the GPS equipment installation.
Findings
- The primary cause of the fire was a human factor involving the improper installation of a GPS Intel-flow cable. This cable was in constant contact with an aircraft metal component, and the resulting mechanical vibration and motion wore through the wire insulation, leading to a short circuit.
- A lack of established maintenance schedules for inspecting installed GPS equipment contributed to the incident.
- There was a lack of proper documentation, as no technical data regarding the GPS installation had been submitted to or approved by the CAAP Flight Standards Inspectorate Service (FSIS).