What happened
On a flight from Cayo Largo Del Sur, Cuba, to Montréal / Mirabel International Airport, a Boeing 737-200, registration C-FRYG, experienced a significant loss of oil in its right engine. Approximately 20 minutes after departure, the flight crew noticed fluctuating oil pressure and a low oil level in the P&W JT8D-9A engine. Following established procedures, the crew shut down the engine and declared an emergency, electing to divert to Fort Lauderdale Airport, Florida.
While the aircraft was in a holding pattern, passengers reported seeing sparks beneath the right engine nacelle. Shortly thereafter, the crew received multiple cockpit warnings, including an engine overheat light and an engine fire alarm. Although the crew discharged both onboard fire extinguisher bottles into the engine nacelle, the fire remained uncontrolled. The aircraft landed on Runway 27R at Fort Lauderdale, where it came to a stop and was immediately evacuated. Emergency responders worked to extinguish the blaze, which was particularly difficult to combat because it involved the magnesium alloy of the accessory gearbox.
The investigation
The TSB examined the engine components, including the accessory gearbox and the oil-fuel cooler, at facilities in Miami. The investigation focused on why the engine caught fire while windmilling and the cause of the initial oil loss. Analysis of the flight data recorder confirmed the engine shutdown occurred 20 minutes after takeoff, though the recorder provided limited parameters for the investigation. The investigation also reviewed the crew's decision-making process regarding the diversion and the suitability of the chosen airport.
Findings
- The loss of oil reduced lubrication to the accessory gearbox, which likely increased internal temperatures enough to ignite the magnesium casing.
- The engine fire extinguishing system, while meeting all certification standards, was not designed to extinguish a magnesium fire.
- The flight crew's decision to enter a holding pattern and prolong the flight increased the risk to the passengers and crew.
- There is a lack of clear definition from the aircraft manufacturer regarding what constitutes the "nearest suitable airport" during an emergency.
Safety action
Following the investigation, Boeing conducted a review of its Operations Manual regarding instructions to land at the nearest suitable airport. Consequently, Boeing updated the Flight Crew Training Manual for all its aircraft to provide clearer guidance on how to apply the concept of a "suitable airport" during non-normal operations.