Response to engine failure downed Metro

 - January 26, 2007, 11:02 AM

The UK’s Air Accidents Investigation Branch (AAIB) released its final report on the 2002 crash of a Swearingen SA227-AC Metroliner III at Aberdeen Airport, Scotland. The accident followed failure of the right engine shortly after takeoff.

The crew was taking off from Aberdeen to return to Aalborg Airport, Denmark, after completing a 14-day mail contract. The copilot, who was the pilot flying for this departure, held a commercial pilot certificate, with 1,300 hours total time and 275 hours in type. The aircraft commander, who was the pilot not flying, had 4,600 hours total time, with 2,800 hours in type.

The departure runway was 16, with wind 12 knots at 150 degrees, visibility 1.5 miles in mist; clouds scattered at 100 feet and overcast at 200 feet. The controller watched the initial departure before transferring attention to the next aircraft, and four minutes later instructed the Metroliner crew to report turning left, but received no reply.

The calculated takeoff weight of 12,000 pounds was well below the mtow of 16,000 pounds, and in view of the 5,900 feet of runway available the crew elected to carry out a reduced-power takeoff with 25 percent flaps. The captain handled the power setting. On the takeoff roll the crew considered that the aircraft was performing normally and at 100 knots it was rotated to 15 degrees.

As the aircraft broke ground the copilot felt it yawing to the right and he could smell smoke. He told the captain that he suspected an engine failure, called for full power and tried to maintain control with rudder and aileron. The captain felt the aircraft roll about 15 degrees to the right and agreed that the right engine had failed. He did not raise the landing gear as there was no rate of climb indicated.

There were no audio or visual engine warnings, but as the captain moved both power levers forward he noted that the EGT on the right engine was indicating 600 degrees C while the left engine was at more than its 650-degree C limit and the fuel bypass light was on.

The captain retarded the power lever until the bypass light went out and noted the EGT at 630 degrees C. As the aircraft continued to turn to the right the copilot called that he was losing control and the captain activated the right engine stop and feather control. As he did so the aircraft struck the ground with its right wing, sliding across a field and onto a road, coming to rest after hitting a car. The pilot saw that the right wing was on fire and both crewmembers evacuated after shutting down the left engine and discharging both engine fire extinguishers.

The copilot checked on the condition of the car occupants. An intense fire forced the crew to move away from the aircraft. After arrival of the fire and rescue services, the fire was quickly extinguished and all occupants of both the aircraft and the car were accounted for. There were no serious injuries.

Birdstrike
In its report on the accident, the AAIB noted that the cockpit voice recorder produced little relevant information due to an intermittent solder joint on the power-supply board and that there was similar intermittent difficulty with the flight data recorder (FDR).

Investigators found the remains of four birds between 1,700 and 3,000 feet from the threshold of the runway, and strip inspection of the engines established that while there was no evidence of bird ingestion in the right (failed) engine a small residue was found in the combustion chamber of the left engine. While engine failure after V1 is a potential emergency, this aircraft was well below mtow and the crew should have been able to fly safely away. The captain felt that the copilot did not make full use of the available rudder deflection, with resulting airframe drag, while a usable element of the FDR readout showed the airplane achieved a maximum airspeed of 128 knots, 19 knots higher than V2, indicating that the crew did not use a potential climb capability.

Both pilots were type qualified but worked for different employers. The company that held the mail contract employed the copilot, but hired the aircraft and commander from another company. On the positioning flight to Aberdeen at the start of the contract, the commander conducted a line check on the copilot that he believed validated him for working within the operating company authorization. However, the AAIB concluded that the copilot should have undergone a full conversion course to meet JAR-OPS requirements. This deficiency may have led to lack of coordination during the emergency.