What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
On 11/24/2015, EMB-110, N117WA on axsa flight # 1032 was in cruise at 5000 feet after departing mht to lew. The pilot felt and heard a strong surge from the right engine, the aircraft yawed to the right. The pilot noted the temp was rapidly increasing well into the yellow, he pulled back the throttle, feathered and secured the engine. He saw no evidence of fire, so he diverted into pwm, where he landed safely. Preliminary inspection revealed metal in the exhaust with evidence of extreme heat. The initial visual and boroscope inspection showed extensive damage to the compressor turbine, power turbine and combustion liner. There was also evidence of damage to the compressor. The entire engine (gas gen s/n PCE56392 / pwr sec pce 56432) was removed and taken to the wiggins maintenance base in mht and then shipped to prime turbines in hyannis, MA. For teardown and analysis, with the following findings:
1. Pt blade failure noted visually through exhaust duct port. Dents noted in exhaust duct.
2. All CT blades damaged at ½ length and burnt. Extensive damage to CT shroud and segments.
3. Pt stator housing had a hole at 4 o?clock position. Pt stator had rotated with all T-5 probes missing. There was a section of the pt stator missing. Pt stator baffle was separated from stator and damaged. Pt blades all extensively damaged.
4. Removed nozzles and combustion liner ? Found the missing section of pt stator laying in large exit duct - a hole was found in inner sidewall of liner ? At same position as hole in stator housing.
5. CT disc assembly and small exit duct assembly were removed, large exit duct removed. Leading edge of CT vane airfoils had no signs of impact damage.
6. All gas generator case diffuser tubes are intact, with no signs of damage. First stage of compressor inspected with mirror, normal wear noted. No evidence of FOD.
7. Removed exhaust duct and found pt shaft housing has sheared 360 degrees at base flange. No damage noted on first stage sun gear. The rgb housing was split and noted 2nd stage reduction gear box ring gear had one retainer cracked. The power section was not disassembled further.
8. Removed compressor assembly from gas case to investigate the possibility of FOD ingestion. Disassembled the compressor stack. Normal wear and erosion noted on 1st and 2nd stage blades, stators and spacers. The 3rd stage blades, stator and spacer all sustained significant damage. The impeller and impeller housing have rubbed. We attribute this damage to be the result of the CT disc and blade damage and the imbalance resulting from the power section damage.
Conclusion - it appears that initially the pt stator failed and a 3 inch section exited through the stator housing and into the combustion liner. The stator failure likely caused contact with the CT disc and CT blades and pt disc and pt blades which immediately led to the engine failure.
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As the FAA filed it
ON 11/24/2015, EMB-110, N117WA ON AXSA FLIGHT # 1032 WAS IN CRUISE AT 5000 FEET AFTER DEPARTING MHT TO LEW. THE PILOT FELT AND HEARD A STRONG SURGE FROM THE RIGHT ENGINE, THE AIRCRAFT YAWED TO THE RIGHT. THE PILOT NOTED THE TEMP WAS RAPIDLY INCREASING WELL INTO THE YELLOW, HE PULLED BACK THE THROTTLE, FEATHERED AND SECURED THE ENGINE. HE SAW NO EVIDENCE OF FIRE, SO HE DIVERTED INTO PWM, WHERE HE LANDED SAFELY. PRELIMINARY INSPECTION REVEALED METAL IN THE EXHAUST WITH EVIDENCE OF EXTREME HEAT. THE INITIAL VISUAL AND BOROSCOPE INSPECTION SHOWED EXTENSIVE DAMAGE TO THE COMPRESSOR TURBINE, POWER TURBINE AND COMBUSTION LINER. THERE WAS ALSO EVIDENCE OF DAMAGE TO THE COMPRESSOR. THE ENTIRE ENGINE (GAS GEN S/N PCE56392 / PWR SEC PCE 56432) WAS REMOVED AND TAKEN TO THE WIGGINS MAINTENANCE BASE IN MHT AND THEN SHIPPED TO PRIME TURBINES IN HYANNIS, MA. FOR TEARDOWN AND ANALYSIS, WITH THE FOLLOWING FINDINGS:
1. PT BLADE FAILURE NOTED VISUALLY THROUGH EXHAUST DUCT PORT. DENTS NOTED IN EXHAUST DUCT.
2. ALL CT BLADES DAMAGED AT ½ LENGTH AND BURNT. EXTENSIVE DAMAGE TO CT SHROUD AND SEGMENTS.
3. PT STATOR HOUSING HAD A HOLE AT 4 O?CLOCK POSITION. PT STATOR HAD ROTATED WITH ALL T-5 PROBES MISSING. THERE WAS A SECTION OF THE PT STATOR MISSING. PT STATOR BAFFLE WAS SEPARATED FROM STATOR AND DAMAGED. PT BLADES ALL EXTENSIVELY DAMAGED.
4. REMOVED NOZZLES AND COMBUSTION LINER ? FOUND THE MISSING SECTION OF PT STATOR LAYING IN LARGE EXIT DUCT - A HOLE WAS FOUND IN INNER SIDEWALL OF LINER ? AT SAME POSITION AS HOLE IN STATOR HOUSING.
5. CT DISC ASSEMBLY AND SMALL EXIT DUCT ASSEMBLY WERE REMOVED, LARGE EXIT DUCT REMOVED. LEADING EDGE OF CT VANE AIRFOILS HAD NO SIGNS OF IMPACT DAMAGE.
6. ALL GAS GENERATOR CASE DIFFUSER TUBES ARE INTACT, WITH NO SIGNS OF DAMAGE. FIRST STAGE OF COMPRESSOR INSPECTED WITH MIRROR, NORMAL WEAR NOTED. NO EVIDENCE OF FOD.
7. REMOVED EXHAUST DUCT AND FOUND PT SHAFT HOUSING HAS SHEARED 360 DEGREES AT BASE FLANGE. NO DAMAGE NOTED ON FIRST STAGE SUN GEAR. THE RGB HOUSING WAS SPLIT AND NOTED 2ND STAGE REDUCTION GEAR BOX RING GEAR HAD ONE RETAINER CRACKED. THE POWER SECTION WAS NOT DISASSEMBLED FURTHER.
8. REMOVED COMPRESSOR ASSEMBLY FROM GAS CASE TO INVESTIGATE THE POSSIBILITY OF FOD INGESTION. DISASSEMBLED THE COMPRESSOR STACK. NORMAL WEAR AND EROSION NOTED ON 1ST AND 2ND STAGE BLADES, STATORS AND SPACERS. THE 3RD STAGE BLADES, STATOR AND SPACER ALL SUSTAINED SIGNIFICANT DAMAGE. THE IMPELLER AND IMPELLER HOUSING HAVE RUBBED. WE ATTRIBUTE THIS DAMAGE TO BE THE RESULT OF THE CT DISC AND BLADE DAMAGE AND THE IMBALANCE RESULTING FROM THE POWER SECTION DAMAGE.
CONCLUSION - IT APPEARS THAT INITIALLY THE PT STATOR FAILED AND A 3 INCH SECTION EXITED THROUGH THE STATOR HOUSING AND INTO THE COMBUSTION LINER. THE STATOR FAILURE LIKELY CAUSED CONTACT WITH THE CT DISC AND CT BLADES AND PT DISC AND PT BLADES WHICH IMMEDIATELY LED TO THE ENGINE FAILURE.
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