Engine Shutdown Following Erroneous EGT Readings on Peruvian Boeing 737

Casualties unknown • PE

A Peruvian Airlines Boeing 737-300 was forced to return to Tarapoto after the crew shut down engine number one due to an apparent exhaust gas temperature excursion.

What happened

On January 19, 2018, a Boeing 737-300, registration OB-2089-P, operated by Peruvian Air Line S.A.C., departed Tarapoto Airport for Lima under Instrument Flight Rules (IFR). Approximately 20 minutes into the flight, while cruising at 33,000 feet, the pilot in command observed that the Exhaust Gas Temperature (EGT) on engine number one had exceeded operational limits, reaching approximately 1,290 °C, which triggered a warning light.

Following the procedures outlined in the Quick Reference Handbook (QRH), the technical crew decided to perform a commanded shutdown of engine number one. The crew declared an emergency and executed an escape route to return to Tarapotomy. The aircraft landed safely at Tarapoto at approximately 12:04 local time. There were no injuries among the 152 people on board, and the aircraft sustained no damage.

The investigation

The CIAA investigation focused on the EGT indication system, specifically the electrical signal transmission chain, which includes the thermocouple harness, the Terminal Interface T1012, various connectors, and the EGT indicator.

Investigators found that maintenance personnel had applied an incorrect troubleshooting procedure. Instead of using the procedure for EGT indication problems (ATA 71-00-54), which covers fluctuations and high/low readings during cruise, the technicians applied a procedure intended for high EGT specifically during takeoff (ATA 71-00-42). This error led to an incomplete inspection of the signal chain. While the Terminal Interface T1012 was replaced, the investigation noted that the underlying cause of the erroneous readings was not properly addressed through the correct diagnostic path, and the fault recurred the following day.

Findings

  • Improper maintenance processes led to the recurrence of erroneous EGT indications during the cruise phase, which prompted the engine shutdown and emergency declaration.
  • Inadequate quality control and inspection processes during both previous and subsequent corrective actions.
  • The selection of an inappropriate troubleshooting manual reference by maintenance personnel.
  • Inadequate training for the personnel involved in the corrective actions performed on the day of the incident.

Probable cause

The probable cause was the application of incorrect maintenance processes, which resulted in recurring erroneous high EGT indications on engine number one, forcing the pilot to shut down the engine and declare an emergency.

Frequently asked questions

What happened in the 2018-01-19 aircraft accident near PE?

A Peruvian Airlines Boeing 737-300 was forced to return to Tarapoto after the crew shut down engine number one due to an apparent exhaust gas temperature excursion.

What aircraft was involved and where did it happen?

The accident on 2018-01-19 involved a aircraft, registration OB-2089-P, at PE.

What was the probable cause of the accident?

The probable cause was the application of incorrect maintenance processes, which resulted in recurring erroneous high EGT indications on engine number one, forcing the pilot to shut down the engine and declare an emergency.

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