Kaman HH-43F accident near Metaline Falls, Washington, August 18, 2006
On August 18, 2006 at about 11:00 pm local time, a Kaman HH-43F (helicopter), registered N559D, was destroyed in an accident near Metaline Falls, Washington. It was an external-load flight under external-load helicopter rules (Part 133). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The failure of the left-hand cross-shaft input internal spline while the helicopter was in a hover, which resulted in the loss of gear box timing, in-flight blade contact and separation, and the subsequent loss of control and impact with a log deck.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 18, 2006 · about 11:00 pm local time
- Place
- Metaline Falls, Washington · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Kaman HH-43F
- Registration
- N559D · no longer on the register · serial 62-4514
- Damage
- Destroyed
- Flight
- External-load flight · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
The pilot was about to release a load of logs onto a log pile from an altitude between 150 to 200 feet when ground crewmen heard an explosion, then observed the helicopter descend in a nose down attitude before impacting the log deck. An examination of the accident site by an FAA inspector revealed that all major portions of the helicopter were accounted for. A subsequent examination of the wreckage revealed a failure of the transmission's left-hand cross-shaft internal spline, which resulted in the loss of gearbox timing and subsequent in-flight blade contact and separation. Maintenance records revealed that the helicopter's transmission was overhauled on May 1, 2006; the time between the overhaul and the accident was 409.4 hours. An examination of the fractured transmission center housing was caused by two fatigue cracks, which were probably caused by severe cyclic stresses that resulted from repeated loading and unloading of logs.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: instructor: helicopter; instructor: instrument helicopter; instrument: helicopter; rotorcraft: helicopter
- Flight time: 2,000 hours in all; 897 in this make and model; 400 in the last 90 days
- Last flight review: January 1, 2006
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: left
- Injury: fatal
The aircraft
- Airframe total time: 8,026.8 hours
- Last inspection: continuous airworthiness programme, July 1, 2006; 68.3 hours since
- Maximum gross weight: 6,500 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming T53-L-13B (turboshaft); 0 hours total
The flight
- Departed from: Metaline Falls WA at 10:30 pm
- Destination: Metaline Falls WA
- Flight plan: none
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 84°F (29°C), dew point 37°F (3°C)
- Altimeter: 30.12 inHg
- Observation at 10:53 pm from DEW, 60 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.