What happened
On July 21, 2011, at 10:01 UTC, a Boeing 737-800, registration G-GDFC, operated by Jet2.com, was performing a commercial flight from Ibiza to Manchester. Shortly after rotating and lifting off from runway 06 at Ibiza Airport, the aircraft experienced repeated compressor stalls in the number 2 (right) engine. These stalls were accompanied by visible flames and smoke exiting the engine exhaust, which were observed by both air traffic control and passengers.
Initially, the crew believed a landing gear tire had burst, which temporarily interrupted the landing gear retraction sequence. However, within 26 seconds, the crew identified a failure in the right engine. Approximately 50 seconds after the initial event, as vibrations increased and Exhaust Gas Temperature (EGT) exceeded limits, the crew elected to shut down the right engine.
The crew declared a MAYDAY and, following established emergency procedures, decided to divert to Palma de Mallorca rather than returning to Ibiza. The aircraft maintained an altitude of 3,000 ft and performed holding patterns near the MJV VOR to allow for weight calculations and emergency checklists. The aircraft eventually performed a stabilized approach and a smooth landing on runway 24L at Palma de Mallorca. There were no injuries among the 180 passengers or the 6 crew members.
The investigation
The investigation focused on the mechanical failure of the CFM56-7B engine. Technical analysis of the flight data recorder (DFDR) and cockpit voice recorder (CVR) confirmed the sequence of compressor stalls and the crew's timely engine shutdown.
Post-flight inspections of the engine revealed internal damage, including damage to the tips of the 8th stage high-pressure compressor (HPC) blades and significant deterioration of the high-pressure turbine (HPT) blades. While there was no widespread fire, investigators found evidence of localized oil combustion within the engine casing caused by friction between seals due to increased shaft clearance.
Laboratory analysis of the engine components was conducted to identify the root cause of the failure. The investigation examined the condition of the bearings, the lubrication system, and the presence of any contaminants in the magnetic chip detectors (MCD).
Findings
- The primary cause of the engine failure was the total failure of bearing #4.
- The failure originated from spalling (material flaking) on the outer race and the rollers of the bearing.
- This spalling caused the bearing cage to break due to fatigue from cyclic loading.
- The resulting increase in shaft clearance led to friction between the engine seals, which ignited the engine oil and caused localized damage.
- The compressor stalls were a secondary effect of the increased rotational resistance in the low-pressure spool caused by the bearing degradation.
- No prior warnings were available via vibration monitoring or magnetic chip detectors, as the failure was sudden and the metal particles were not detected in the preceding weeks.