Boeing 707-321C – 5N-MAS

Incident Overview

Date: Tuesday 31 March 1992

Aircraft Type: Boeing 707-321C

Owner/operator: Trans-Air Service

Registration Number: 5N-MAS

Location: Istres – ÿ France

Phase of Flight: En route

Status: Destroyed, written off

Casualties: Fatalities: 0 / Occupants: 5

Component Affected: Right Inboard Engine Pylon FittingRight Inboard Engine Pylon Fitting

Category: Accident

On March 3, 1992, a Boeing 707, carrying 38 tonnes of freight, experienced a significant incident during an IFR flight to Kano. The aircraft was flying at 280 knots IAS, passing VILAR and the VOR of Martigues, when the crew detected severe turbulence and heard a double ‘bang’. The aircraft then rolled to the right, causing the captain to struggle with control. The autopilot was disengaged, and the crew initiated a descent towards Marseilles, then transferred to Istres Control. A left-hand circuit was flown for a runway 15 landing at Istres. During the landing, the no. 4 engine separated, sending a Mayday call, and the crew initiated fuel dumping. A fire erupted on the right wing, which was put out by the fire engineer. The aircraft subsequently experienced a left-hand circuit, stopping 250 meters off the centreline, and the left main gear tires burst. The flight engineer selected maximum reverse thrust, and the aircraft drifted off the runway, resulting in a 190 knots speed. The incident was reported to be a result of a fracture in the right inboard engine pylon fitting, exacerbated by periodic monitoring of the midspar fitting, which proved insufficient.On March 3, 1992, a Boeing 707, carrying 38 tonnes of freight, experienced a significant incident during an IFR flight to Kano. The aircraft was flying at 280 knots IAS, passing VILAR and the VOR of Martigues, when the crew detected severe turbulence and heard a double ‘bang’. The aircraft then rolled to the right, causing the captain to struggle with control. The autopilot was disengaged, and the crew initiated a descent towards Marseilles, then transferred to Istres Control. A left-hand circuit was flown for a runway 15 landing at Istres. During the landing, the no. 4 engine separated, sending a Mayday call, and the crew initiated fuel dumping. A fire erupted on the right wing, which was put out by the fire engineer. The aircraft subsequently experienced a left-hand circuit, stopping 250 meters off the centreline, and the left main gear tires burst. The flight engineer selected maximum reverse thrust, and the aircraft drifted off the runway, resulting in a 190 knots speed. The incident was reported to be a result of a fracture in the right inboard engine pylon fitting, exacerbated by periodic monitoring of the midspar fitting, which proved insufficient.

Description

The Boeing 707 took off from Luxembourg at 07:14 for an IFR flight to Kano, carrying 38 tonnes of freight. The aircraft, on a heading of 199deg, when passing VILAR and the VOR of Martigues, was authorized to leave FL290 for FL330. This flight section was performed in IMC in turbulent air. With the throttles at climb power and autopilot engaged the aircraft was flying at 280 knots IAS passing FL320. At this moment, the crew was experiencing severe turbulence and heard a double ‘bang’. The aircraft suddenly rolled to the right. The captain disengaged autopilot and struggled to keep control by countering with control stick and rudder pedals. The continuous fire warning system sounded, but could not be switched off by the flight engineer. The first officer noted that the no. 4 engine had separated and sent out a Mayday call (at 08:11). The crew started the descend towards Marseilles and initiated the fuel dumping procedure. During the descent the first officer noted an airfield ahead (which was Istres) and was Marseilles transferred the aircraft to Istres Control. A left hand circuit was flown for a runway 15 landing at Istres. The plane touched down slightly to the left of the centreline at a 190 knots speed. Emergency brakes had to be used to decelerate. The left main gear tyres burst during the landing roll and the flight engineer selected maximum reverse thrust on the no. 2 engine. After a 2300 m ground roll, the 707 went off the left side of the runway and stopped 250 m further on. The fire on the right wing (which had erupted in the final approach phase) was put out. The landing took place at 08.35, about 24 min after engine separation. The aircraft had just been acquired by Trans-Air Service and had started flying on March 3, 1992 after having been stored at Southend since October 24, 1990. Between March 4 and Mach 31 the aircraft had accumulated 116 flying hours in 34 flights. PROBABLE CAUSE: “The accident resulted from the fracture of the right inboard engine pylon fitting, in such conditions that this engine came to hit and tore away the outboard engine. The AD, imposing periodic monitoring of the midspar fitting, proved to be insufficiently efficient.”