DES MOINES, IA, USA
N274SM
BELL 222UT
The pilot reported that approximately one minute after takeoff, the emergency medical service helicopter experienced a left yaw. The nurse and paramedic, who were seated in the back, reported hearing a 'pop.' The number 1 engine-out indicator light illuminated, the pilot reduced the throttle to flight idle, and he made a turn toward the airport to land. The pilot stated that the number 1 engine-fire indicator light illuminated and he armed and discharged the fire extinguisher bottle. An emergency landing was made and the pilot and passengers were able to evacuate without further incident. Postaccident examination revealed that the engine air inlet duct on the left engine had collapsed internally due to delamination. A service bulletin addressing this issue had been complied with.
On June 21, 1995, at 0018 central daylight time, a Bell 222UT emergency medical service helicopter, N274SM, operated by Air Methods Corporation of Englewood, Colorado, experienced a loss of engine power shortly after taking off from Mercy Hospital, Des Moines, Iowa. While making an emergency landing at Des Moines International Airport, the fire warning light illuminated and the pilot activated the fire pull handle discharging the fire extinguisher. The helicopter landed without further incident with minor damage. The pilot, nurse, and paramedic reported no injuries. The 14 CFR Part 91 flight was en route to Cass County Memorial Hospital Heliport, Atlantic, Iowa, to pick up a patient for transport. Visual meteorological conditions prevailed at the time of the accident. The pilot reported that approximately one minute after takeoff, the helicopter experienced a left yaw as if it had encountered some light turbulence. The nurse and paramedic, who were seated in the back, reported hearing a "pop" sound. The number one engine out indicator light illuminated and the pilot immediately lowered the collective. The pilot stated that he reduced the engine's throttle to flight idle after he verified that the number one engine had indeed failed. He then notified Des Moines Approach Control of the emergency and turned the helicopter toward the airport. The number one engine fire indicator light illuminated and the passengers notified the pilot that smoke and heat were entering the cabin. The pilot stated he then armed the number one fire extinguisher and after the engine fire light remained illuminated for a few seconds, he fired the number one agent bottle to discharge the fire extinguisher. The fire light then went out, but the pilot stated the cabin was still filling with smoke. An emergency landing was made and the pilot and passengers were able to evacuate without further incident. Postaccident examination revealed the engine air inlet duct (P/N 222-062-211-103) on the left engine had collapsed internally. The duct was sent to Bell Helicopter Textron in Fort Worth, Texas, for further examination and testing. Examination found the first layer of composite fabric had delaminated from the upper inner surface of the duct which allowed the layer to sag. The final examination report states, "The delamination of the inner composite layer from the duct occurred by fracturing of the resin between the inner surface ply and the adjacent ply of composite material. A visual and microscopic (30x) examination of the delaminated surfaces revealed no evidence of voids or other discrepancies which would have caused the delamination." See attached report. Bell Helicopter Textron Alert Service Bulletin 222U-93-34, dated April 24, 1993, required that the engine air inlet duct be inspected at the next inspection event and at every inspection event #12 thereafter if the Progressive Inspection System is used. Review of N274SM's logbook indicated that the Progressive Inspection System is used. The last inspection event #12 occurred on April 22, 1995, at the total time of 5550.4 hours. The required inspection of the air inlet ducts was performed at this time. The helicopter has logged 89.7 hours since that inspection. Examination of the helicopter's fire detection system revealed that the left fire extinguisher bottle did not discharge. The squib from the bottle was removed and tested. It fired without hesitation. No other anomalies were found in the system.
delamination of the left engine air inlet duct.
Source: NTSB Aviation Accident Database
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