What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
After rotation at approximately 300-400 ft AGL, the flight crew observed a bird to the forward right hand side of the windshield and immediately thereafter they experienced a vibration throughout the aircraft. Climb continued until 9000 ft as the flight crew noticed a vib indication of 3.5 in the lower display unit (du) on the #2 engine that kept increasing significantly. The crew declared pan pan and requested ATC an air turnback to dtw. The impacted engine was still producing power; vib observed ranged between 2.0 and 2.5 once power was set at 67% N1.
During landing, the crew initiated the reverse and quickly stowed the reverses as vibrations increased at it was deployed on the #2 engine. The aircraft then taxied to the terminal with a single engine in operation.
Maintenance findings and actions:
- Overweight inspection carried out with no faults found.
- Damage found on blades 3,4,5,6. When blades were removed and replaced, damage to the containment case was identified as follows:
4 Gouges found on fan blade containment case aft of abradable shroud at positions 11 o’clock and 2:30 o’clock:
Gouge #1 at the 10H position, 14.75" behind A1. It measures 1.25" long, max depth of 0.015".
Gouge #2 at the 2H30 position, 14.5" behind A1. It measures 3.0" long, max depth of 0.027".
Gouge #3 at the 2H30 position. 15.5" behind A1. It measures 1.375" long, max depth 0.017"
Gouge #4 at the 2H30 position. 15.75" behind A1. It measures 1.375" long, max depth 0.017".
- Due to the above-reported findings brought to the attention of cfm, the manufacturer was not confident that the mechanical properties of the containment case were ensured anymore and could potentially damage other parts in a potential fan blade out scenario (material safety margin was degraded). Cfm therefore recommended removing the containment case and replacing it. However, this was logistically challenging as this occurred away from a privacy data omitted maintenance facility.
Since cfm could not provide a 2-cycle dica to position the aircraft, an engine replacement was recommended. The #2 engine was installed on August 03rd and successfully tested.
As the FAA filed it
AFTER ROTATION AT APPROXIMATELY 300-400 FT AGL, THE FLIGHT CREW OBSERVED A BIRD TO THE FORWARD RIGHT HAND SIDE OF THE WINDSHIELD AND IMMEDIATELY THEREAFTER THEY EXPERIENCED A VIBRATION THROUGHOUT THE AIRCRAFT. CLIMB CONTINUED UNTIL 9000 FT AS THE FLIGHT CREW NOTICED A VIB INDICATION OF 3.5 IN THE LOWER DISPLAY UNIT (DU) ON THE #2 ENGINE THAT KEPT INCREASING SIGNIFICANTLY. THE CREW DECLARED PAN PAN AND REQUESTED ATC AN AIR TURNBACK TO DTW. THE IMPACTED ENGINE WAS STILL PRODUCING POWER; VIB OBSERVED RANGED BETWEEN 2.0 AND 2.5 ONCE POWER WAS SET AT 67% N1.
DURING LANDING, THE CREW INITIATED THE REVERSE AND QUICKLY STOWED THE REVERSES AS VIBRATIONS INCREASED AT IT WAS DEPLOYED ON THE #2 ENGINE. THE AIRCRAFT THEN TAXIED TO THE TERMINAL WITH A SINGLE ENGINE IN OPERATION.
MAINTENANCE FINDINGS AND ACTIONS:
- OVERWEIGHT INSPECTION CARRIED OUT WITH NO FAULTS FOUND.
- DAMAGE FOUND ON BLADES 3,4,5,6. WHEN BLADES WERE REMOVED AND REPLACED, DAMAGE TO THE CONTAINMENT CASE WAS IDENTIFIED AS FOLLOWS:
4 GOUGES FOUND ON FAN BLADE CONTAINMENT CASE AFT OF ABRADABLE SHROUD AT POSITIONS 11 O’CLOCK AND 2:30 O’CLOCK:
GOUGE #1 AT THE 10H POSITION, 14.75" BEHIND A1. IT MEASURES 1.25" LONG, MAX DEPTH OF 0.015".
GOUGE #2 AT THE 2H30 POSITION, 14.5" BEHIND A1. IT MEASURES 3.0" LONG, MAX DEPTH OF 0.027".
GOUGE #3 AT THE 2H30 POSITION. 15.5" BEHIND A1. IT MEASURES 1.375" LONG, MAX DEPTH 0.017"
GOUGE #4 AT THE 2H30 POSITION. 15.75" BEHIND A1. IT MEASURES 1.375" LONG, MAX DEPTH 0.017".
- DUE TO THE ABOVE-REPORTED FINDINGS BROUGHT TO THE ATTENTION OF CFM, THE MANUFACTURER WAS NOT CONFIDENT THAT THE MECHANICAL PROPERTIES OF THE CONTAINMENT CASE WERE ENSURED ANYMORE AND COULD POTENTIALLY DAMAGE OTHER PARTS IN A POTENTIAL FAN BLADE OUT SCENARIO (MATERIAL SAFETY MARGIN WAS DEGRADED). CFM THEREFORE RECOMMENDED REMOVING THE CONTAINMENT CASE AND REPLACING IT. HOWEVER, THIS WAS LOGISTICALLY CHALLENGING AS THIS OCCURRED AWAY FROM A ^PRIVACY DATA OMITTED^ MAINTENANCE FACILITY.
SINCE CFM COULD NOT PROVIDE A 2-CYCLE DICA TO POSITION THE AIRCRAFT, AN ENGINE REPLACEMENT WAS RECOMMENDED. THE #2 ENGINE WAS INSTALLED ON AUGUST 03RD AND SUCCESSFULLY TESTED.