Thread link:
http://www.pprune.org/forums/showthr...h&pagenumber=1
Final report:
"The 493-hour pilot reported that approximately 5 minutes after departure, he noticed a "slight change in engine noise." Subsequently, he
heard a "bang," followed by an aural engine warning horn, and a loss of engine power. The pilot initiated an autorotation, and during
the autorotation, the helicopter impacted power lines, landed hard on a parking lot surface and came to rest upright. A witness located
adjacent to the helicopter's flight path reported hearing a "loud backfire" followed by subsequent white smoke coming from the
helicopter. Review of the aircraft maintenance records revealed the engine was overhauled approximately 295 hours prior to the accident.
During the engine overhaul, the impeller travel (bump clearance) was measured to be approximately .010 inches. During the engine
teardown examination, prior to the removal of the compressor rotor from the rear support, the impeller travel (bump clearance) was
measured to be approximately 0.021 inches. The third, fifth, and sixth stage vane assemblies were bent in the direction of rotation.
Corresponding damage was observed on the trailing edges of the blades on the adjacent forward compressor rotors. Fretting and score
marks noted on the compressor assembly components were consistent with axial movement at the compressor assembly resulting in contact
between the compressor blades and vanes, and a subsequent compressor stall and loss of engine power."
and...
"The National Transportation Safety Board determines the probable cause(s) of this accident as follows.
The loss of engine power due to the axial movement of the compressor rotor blades contacting the compressor vanes resulting in a
subsequent compressor stall. A contributing factor was the improper assembly of the compressor section during the engine overhaul by
unknown maintenance personnel.
Accident (Continued)
Occurrence #1: LOSS OF ENGINE POWER
Phase of Operation: CRUISE
Findings
1. (F) MAINTENANCE,OVERHAUL - IMPROPER - OTHER MAINTENANCE PERSONNEL
2. (C) COMPRESSOR ASSEMBLY - SHIFTED
3. COMPRESSOR ASSEMBLY - STALL
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Occurrence #2: FORCED LANDING
Phase of Operation: MANEUVERING - TURN TO LANDING AREA (EMERGENCY)
Findings
4. AUTOROTATION - INITIATED - PILOT IN COMMAND
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Occurrence #3: IN FLIGHT COLLISION WITH OBJECT
Phase of Operation: DESCENT - EMERGENCY
Findings
5. MANEUVER TO AVOID OBSTRUCTIONS - PERFORMED - PILOT IN COMMAND
6. OBJECT - WIRE,TRANSMISSION
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Occurrence #4: HARD LANDING
Phase of Operation: DESCENT - EMERGENCY
Findings
7. TERRAIN CONDITION - GROUND
Findings Legend: (C) = Cause, (F) = Factor
Time (Local): 02:45 CST Aircraft Reg No. N255TP San Antonio, TX 02/19/2004 File No. 16718
FTW04GA076"
Auto at night over a built up area, and they both walked away. Good result alround.