Ther Peruvian Comisión de Investigación de Accidentes de Aviación (CIAA) concluded their investigation into a runway excursion accident at Andahuaylas, Peru. The Metro III airplane had lost directional control on landing due to multiple failures in the brake system.
The Swearingen SA227AC Metro III passenger plane, registered N781C, sustained substantial damage in a runway excursion accident at Andahuaylas Airport (ANS), Peru. All 17 passengers and two crew members survived. The airplane operated on a flight from Huaraz/Anta Airport (ATA).
The accident airplane, N781C, suffered problems with the Nose Wheel Steering (NWS) and had a recurring history of brake system failures. The NWS problems were deferred by maintenance crew. The brake package was changed the day before the accident without troubleshooting the cause of the problems.
On the day of the accident the flight crew had again reported problems controlling the airplane’s direction on the ground. Maintenance crew then eliminated the pressure of the left brake package and bled the right brake system, again without troubleshooting the cause of the problems.
While taxiing out for takeoff on the accident flight, the crew noted the braking problems persisted. Yet, the captain decided to continue the flight with known brake issues and a disconnected NWS. The landing on Andahuaylas Airport (ANS) runway 03 initially went fine. At a ground speed of 40 knots the airplane began to swerve to the left with increasing intensity. The crew applied right hand brakes and put the right hand engine in reverse. This achieved a correction of about 15° but this was still insufficient. The airplane continued left until it went down a 4-metre embankment.