Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Addy, Washington 99101
Tuesady, June 3, 1997 6:30 PDT
NTSB Narrative Summary Released at Completion of Accident
While returning to pick up another log, the pilot heard a high-speed shredding sound' accompanied by high-frequency vibrations. As the noise and vibration increased, the pilot turned downhill and looked for a location where he could make an emergency landing. He then heard a second loud noise, and the rotor RPM immediately began to decay. He stretched his glide over the 130 foot high trees and managed to maneuver the helicopter so that it 'fell into' a switchback on an old dirt logging road. A post accident examination of the K-FLEX drive shaft, which runs between the engine and the transmission, revealed that one of its flex band legs had experienced an inflight fatigue fracture. A review of the records revealed that the shaft had accumulated 459 hours while being used by the United States Army, and had accumulated an additional 432 hours during civilian logging operations.
NTSB Probable Cause Narrative
The inflight failure of the K-FLEX engine-to-gear box drive shaft and no suitable site in which to make a forced/emergency landing. A factor was the mountainous/hilly terrain.
Event Information
| Type of Event | Accident |
| Event Date | 6/3/1997 |
| Event Day of the Week | Tuesday |
| Time of Event | 630 |
| Event Time Zone | Pacific Daylight Time |
| Event City | ADDY |
| Event State | WASHINGTON |
| Event Country | -- |
| Zipcode of the event site | 99101 |
| Event Date Year | 1997 |
| Event Date Month | 6 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | |
| Event Location Longitude | |
| Event Location Airport | |
| Event Location Nearest Airport ID | |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| 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) | 5 |
| Air Temperature at event time (in degrees celsius) | 20 |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | 0 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 0 |
| Wind Velocity Indicator | Calm |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | 0 |
| 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 | 1 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 1568 |
| NTSB Notification Source | -- |
| NTSB Notification Date | Jun 3 1997 12:00AM |
| NTSB Notification Time | 800 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | Dec 8 2000 12:21PM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N85NW |
| NTSB Number | SEA97LA126 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 133: Rotorcraft Ext. Load |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Garlick |
| Aircraft Model | UH-1H |
| Aircraft Series Identifier | UH-1H |
| Aircraft Serial Number | 66-0792 |
| Certified Max Gross Weight | 9500 |
| 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 | 0 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Annual |
| Date of Last Inspection | Jun 1 1997 12:00AM |
| Airframe hours since last inspection | 12 |
| Airframe Hours | 8782 |
| ELT Installed | No |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | NORTHWEST HELICOPTER, INC. |
| Aircraft Owner Street Address | 7822 HIGHWAY 99 SE |
| Aircraft Owner City | OLYMPIA |
| Aircraft Owner State | WA |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 98501 |
| 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 | WYFL |
| 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 | Unknown |
| Indicates Domestic or International Flight | Unknown |
| Operator carrying Pax/Cargo/Mail | Unknown |
| Type of Flying (Per_Bus / Primary) | Other Work Use |
| Second Pilot on Board | No |
| Departure Point Same as Event | Yes |
| Departure Airport Code | |
| Departure City | |
| Departure State | WA |
| Departure Country | |
| Departure Time | 1600 |
| Departure Time Zone | PDT |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | |
| Destination City | |
| Destination State | |
| Destination Country | |
| Specific Phase of Flight | Maneuvering |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jan 2 2001 10:34AM |
| 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 | -- |