Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Mcgrath, Alaska 99627
Friday, September 21, 2007 15:00 AKD
NTSB Narrative Summary Released at Completion of Accident
The airline transport pilot, who was the company owner, and an aviation mechanic, was in cruise flight in a float-equipped airplane when he noticed an engine vibration, followed by a loud bang, and sudden stoppage of the propeller. The pilot described the prop as having suddenly stopped in a feathered position, without windmilling or slowing down. He selected an emergency landing area on a mountain ridge. Just prior to touchdown, the airplane collided with several trees, and nosed over. The pilot had requested and was granted a 100 hour extension beyond the engine overhaul interval of 1,700 hours by his FAA principle maintenance inspector (PMI). The pilot performed 25 hour oil changes and borescoped the engine pursuant to the granting of the 100 hour extension. The number 2 and 6 cylinders were changed about 173.6 hours before the accident, and the number 6 cylinder was changed again, about 60 hours before the accident. At the time of the accident, the engine had about 1,735 hours. Postaccident examination of the engine revealed that one of the number 4 cylinder rod cap bolts was bent 90 degrees, and the bolt threads had been stripped of its retaining nut. The loss of the nut allowed the rod cap to straighten, and then break the opposite cap bolt at its base. The entire number 4 piston and connecting rod departed the engine, breaking the number 4 cylinder away from the engine case. The propeller blade pitch change links within the hub were broken in tension, which the propeller manufacturer indicated was consistent with the blades contacting the ground or striking an object during the accident sequence.
NTSB Probable Cause Narrative
A separation of the engine connecting rod and engine cylinder due to the loss of a connecting rod nut that was stripped from the rod bolt.
Event Information
| Type of Event | Accident |
| Event Date | 9/21/2007 |
| Event Day of the Week | Friday |
| Time of Event | 1500 |
| Event Time Zone | -- |
| Event City | McGrath |
| Event State | ALASKA |
| Event Country | -- |
| Zipcode of the event site | 99627 |
| Event Date Year | 2007 |
| Event Date Month | 9 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 641218N |
| Event Location Longitude | 1561526W |
| 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 | -- |
| Investigator's weather source | Pilot |
| Time of the weather observation | |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | -- |
| Elevation of weather observation facility | -- |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | -- |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 1200 |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | -- |
| Sky Condition for Lowest Ceiling | Broken |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 40 |
| Air Temperature at event time (in degrees celsius) | 12 |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | -- |
| Variable Wind Indicator | Variable |
| Wind Speed (knots) | -- |
| Wind Velocity Indicator | Light and Variable |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | -- |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | Minor |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | 2 |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 2 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 23981 |
| NTSB Notification Source | FAA Regional Operations Center |
| NTSB Notification Date | Sep 21 2007 12:00AM |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Jul 30 2008 9:00AM |
| User who most recently changed record | NTSB\johb |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | FAA-AL-ANC FSDO 03 |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N8030Z |
| NTSB Number | ANC07LA104 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | VFR |
| Flight plan Was Activated? | Yes |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Cessna |
| Aircraft Model | U206 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | U206-0430 |
| Certified Max Gross Weight | 3500 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 2 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Annual |
| Date of Last Inspection | Aug 1 2007 12:00AM |
| Airframe hours since last inspection | 60 |
| Airframe Hours | 6527 |
| ELT Installed | Yes |
| ELT Activated | Yes |
| ELT Aided Location of Event Site | Yes |
| ELT Type | -- |
| Aircraft Owner Name | Scenic Mountain Air Inc. |
| Aircraft Owner Street Address | P.O. Box 4 |
| Aircraft Owner City | Moose Pass |
| Aircraft Owner State | AK |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 99631 |
| Operator is an individual? | No |
| Operator Name | Vernon Kingsford |
| Operator Same as Owner? | No |
| 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 | -- |
| Other Operator of large aircraft? | -- |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | -- |
| Indicates Domestic or International Flight | -- |
| Operator carrying Pax/Cargo/Mail | -- |
| Type of Flying (Per_Bus / Primary) | Positioning |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | PAGA |
| Departure City | Galena |
| Departure State | AK |
| Departure Country | USA |
| Departure Time | 1430 |
| Departure Time Zone | ADT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | 52Z |
| Destination City | Moose Pass |
| Destination State | AK |
| Destination Country | USA |
| Specific Phase of Flight | Cruise |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jul 23 2008 2:32PM |
| User who most recently changed record | STAM |
| Since inspection or accident | Last Inspection |
| Event Location Runway Number and Location | NA |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |