Individually Owned: 150,657
Corporate Owned: 137,281
Iliamna Bay Airport
Aircraft Accident/Incident Report
Williamsport, Alaska
Saturday, April 21, 1990 13:10 AKD
NTSB Narrative Summary Released at Completion of Accident
THE HELICOPTER PILOT REPORTED A TOTAL LOSS OF POWER AND A SUBSEQUENT HARD AUTOROTATION LANDING. AN EXAMINATION OF THE ENGINE DISCLOSED A FRACTURED PC TUBE FROM THE COMPRESSOR TO THE PC FILTER. FAILURE OF THIS TUBE WILL CAUSE THE ENGINE TO LOSE POWER BELOW IDLE OR FLAME OUT. AN NTSB METALLURGIST WHO EXAMINED THE TUBE BELIEVES THAT THE TUBE FRACTURED DUE TO FRETTING AND FATIGUE, MOST LIKELY PRECIPITATED BY MISALIGNMENT OF THE PC TUBE DURING FIELD MAINTENANCE. ALLISON, THE ENGINE MANUFACTURER, HAS RECENTLY REDESIGNED THE TUBE WITH A THICKER WALL AND A DIFFERENT SHAPE TO FACILITATE MAINTENANCE PROCEDURES IN THE FIELD, AND TO MAKE THE TUBE MORE RESISTANT TO FATIGUE.
NTSB Probable Cause Narrative
THE MANUFACTURER'S INADEQUATE PART DESIGN AND THE IMPROPER MAINTENANCE TECHNIQUES BY THE OPERATOR.
Event Information
| Type of Event | Accident |
| Event Date | 4/21/1990 |
| Event Day of the Week | Saturday |
| Time of Event | 1310 |
| Event Time Zone | -- |
| Event City | WILLIAMSPORT |
| Event State | ALASKA |
| Event Country | -- |
| Zipcode of the event site | |
| Event Date Year | 1990 |
| Event Date Month | 4 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | |
| Event Location Longitude | |
| Event Location Airport | ILIAMNA BAY |
| Event Location Nearest Airport ID | NONE |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | 0 |
| Degrees magnetic from airport | 0 |
| Airport Elevation | -- |
| Weather Briefing Completeness | Unknown |
| Investigator's weather source | Pilot |
| Time of the weather observation | 0 |
| Direction of event from weather observation facility (degrees) | 0 |
| Weather Observation Facility ID | |
| Elevation of weather observation facility | 0 |
| Distance of event from weather observation facility (units?) | 0 |
| Time Zone of the weather observation | |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 0 |
| Lowest Non-Ceiling Height | 0 |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | 0 |
| Visibility Runway Visual Value (Statute Miles) | 0 |
| Visibility (Statute Miles) | 100 |
| Air Temperature at event time (in degrees celsius) | 4 |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | 115 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 10 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Unknown |
| Wind Gust (knots) | 5 |
| Altimeter Setting at event time (in. Hg) | -- |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 4 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 480 |
| NTSB Notification Source | -- |
| NTSB Notification Date | -- |
| NTSB Notification Time | 131 |
| Fiche Number and/or location -used to find docket information | 41414 |
| Date of most recent change to record | Mar 17 2006 2:53PM |
| User who most recently changed record | NTSB\ZUZL |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N1075G |
| NTSB Number | ANC90LA063 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 135: Air Taxi & Commuter |
| Type of Flight Plan filed | VFR |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | BELL |
| Aircraft Model | 206B3 |
| Aircraft Series Identifier | 206B3 |
| Aircraft Serial Number | 2958 |
| Certified Max Gross Weight | 3200 |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 5 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Annual |
| Date of Last Inspection | Apr 14 1990 12:00AM |
| Airframe hours since last inspection | 20 |
| Airframe Hours | -- |
| ELT Installed | Yes |
| ELT Activated | Yes |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | MARITIME HELICOPTERS |
| Aircraft Owner Street Address | 3520 FAA ROAD |
| Aircraft Owner City | HOMER |
| Aircraft Owner State | AK |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 99603 |
| Operator is an individual? | -- |
| Operator Name | |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | |
| Operator City | |
| Operator State | |
| Operator Country | |
| Operator Zip code | |
| Operator Code | |
| Owner has at least one certificate | Yes - certificate holder |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | External Load |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | Non-scheduled |
| Indicates Domestic or International Flight | Domestic |
| Operator carrying Pax/Cargo/Mail | Passenger Only |
| Type of Flying (Per_Bus / Primary) | Unknown |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | HOM |
| Departure City | HOMER |
| Departure State | AK |
| Departure Country | |
| Departure Time | 1049 |
| Departure Time Zone | ADT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | HOM |
| Destination City | HOMER |
| Destination State | AK |
| Destination Country | |
| Specific Phase of Flight | Landing |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jan 2 2001 10:35AM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 0 |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |