Event Overview
On October 2, 2021, at about 17:44 Eastern Standard Time, Spirit Airlines flight 3044, an Airbus A320-271N neo (registration N922NK) powered by two International Aero Engines PW1127G-JM geared turbofans, experienced a bird strike and subsequent fire in the right (No. 2) engine during takeoff roll at Atlantic City International Airport (ACY), New Jersey. The flightcrew received a No. 2 engine fire warning, discharged both fire bottles, and aborted the takeoff at a groundspeed of about 100 knots, stopping the aircraft on the runway. Emergency slides were deployed, and passengers evacuated onto the runway. Airport Aircraft Rescue and Firefighting (ARFF) personnel responded. Of the 102 passengers, 6 crew members, and one dead-heading crew member on board, four minor injuries were reported during the evacuation. The flight was a scheduled domestic passenger service to Fort Lauderdale-Hollywood International Airport, Florida, operating under 14 CFR Part 121.
Aircraft and Engine Examination
On-scene examination revealed no visible impact damage to the airframe or wing from exiting engine debris. The right engine’s outboard thrust reverse translating sleeve exhibited thermal distress longitudinally from just aft of the fan cowl-to-outer translating sleeve interface and circumferentially from about the 4:00 to 6:00 o’clock positions, including blistered paint and minor sleeve skin damage without burn-through holes. Minor discoloration of thermal blankets was noted on the inboard and outboard thrust reverser inner fixed structure and bifurcation panel.
Engine inspection showed one fan blade fractured near the root above the platform, resulting in a complete airfoil release. A portion of the fractured blade was found wedged in the fan case rub strip at about the 9:00 o’clock position; no uncontainments or breaches of the fan case assembly were observed. The root portion of the fractured blade remained in the fan disk hub with a shiny, clean fracture surface. Several adjacent fan blades exhibited pronounced S-shaped bending from approximately 50% span to the tip, along with impact damage, tears, and missing material in the direction opposite rotation. A large quantity of bird remains (snarge) was present on the forward acoustic liner and fan exit guide vanes.
Bird Strike Analysis
The United States Department of Agriculture (USDA) Wildlife Biologist District Supervisor collected bird remains from the engine and sent them to the Smithsonian Institution Feather Identification Laboratory. The bird remains were identified as a male immature Bald Eagle with a mean mass of approximately 4,130 grams (9.1 pounds). The Federal Aviation Administration’s large bird ingestion certification test weight requirement for the PW1127G-JM engine inlet throat area is 2.75 kilograms (6.05 pounds), making the ingested bird larger than the certification requirement. Review of the large bird ingestion certification test showed only partial fan blade airfoil material release on several blades, not a full airfoil release as observed in this event. Additionally, the test was conducted on a test rig without the TMS manifold or CP-09 fuel tube installed, precluding direct comparison.
Fuel Leak and Ignition Source Analysis
On-wing fuel leak testing using the right wing tank boost pumps revealed fuel exiting from behind the fuel-oil heat exchanger (FOHE) and fuel-oil cooler generator on the left side of the engine. Due to obstructed visibility, testing was terminated, and the engine was sent to the Pratt & Whitney Columbus Engine Center. There, two fractured bolts on the TMS manifold lower aft support bracket and a cracked CP-09 fuel tube were discovered. Metallurgical evaluation of the CP-09 tube indicated material composition consistent with specifications. The fracture exhibited transgranular fatigue with multiple origins along the outer diameter and necked-down wall thickness at the fracture, attributed to stretching following bolt fracture from the bird strike, not a manufacturing defect. The two TMS manifold bolts showed dimple fracture features indicative of overstress.
Airbus and IAE analyzed potential ignition sources for the fuel leak. They concluded that main landing gear wheel brake temperatures were insufficient to ignite fuel due to distance and vapor concentration. However, IAE estimated that the turbine intermediate case, low-pressure turbine case, and turbine exhaust case—all downstream of the cracked CP-09 tube—reached temperatures sufficient for hot surface ignition of the leaking fuel.
Proposed Design Changes
Based on this and similar bird strike events, IAE has proposed fan blade design changes including thickening the leading edge root, modifying the leading edge sheath for increased bonding, and altering platform geometry. For the TMS mount structure, IAE is redesigning to add more bolts to both upper and lower aft mounts and considering mount structure modifications for improved load distribution to mitigate fire risk by preventing TMS movement and subsequent CP-09 fuel tube damage. Fan blade redesign is projected for fleet incorporation in the third quarter of 2023; TMS redesign details and timing are not yet finalized.