Individually Owned: 150,657
Corporate Owned: 137,281
N/A Airport
Aircraft Accident/Incident Report
Mackinaw City, Michigan 49701
Friday, August 30, 2013 20:15 CDT
NTSB Narrative Summary Released at Completion of Accident
The pilot reported that the motor-glider was on a long, straight-in visual approach to land when he heard a very loud “bang” in the front of the motor-glider followed by a severe vibration. The pilot shut down the engine and made a forced landing to a field. A postaccident examination of the aircraft revealed that the flexible disk on the front of the driveshaft had disconnected. Only one of the three bolts that connected the disk to the driveshaft remained partially installed. No evidence of Loctite or torque paint was found on the bolt. The bolt’s threads were rusted, and the bolt’s head was digging into the gearbox housing. The second bolt was sheared off, and the third bolt was missing.
A review of maintenance records revealed that the motor-glider’s most recent annual inspection was completed about 1 month before the accident. According to the manufacturer’s maintenance manual, a mechanic was required to check the tightness of the bolt connections of the flexible disk on the front side of the drive shaft. It is likely that the mechanic improperly inspected the bolts that connected the flexible joint to the front side of the driveshaft during the last annual inspection, which resulted in the ultimate failure of these components.
The maintenance records also revealed that, during the last annual inspection, Federal Aviation Administration Airworthiness Directive (AD) 2006-19-08, which required inspection for deformations and cracks in the exhaust pipes and the replacement of any damaged exhaust pipes found, had not been properly complied with when a weld repair was made to the No. 1 exhaust pipe. The mechanic’s failure to not properly comply with the AD and the operator’s failure to ensure that the AD was complied with were not causal to the accident; however, because the AD was not complied with, the motor-glider was not considered airworthy.
NTSB Probable Cause Narrative
The mechanic’s failure to inspect the tightness of the bolts that connected the flexible disk to the driveshaft, which resulted in the failure of these components.
Event Information
| Type of Event | Accident |
| Event Date | 8/30/2013 |
| Event Day of the Week | Friday |
| Time of Event | 2015 |
| Event Time Zone | Central Daylight Time |
| Event City | Mackinaw City |
| Event State | MICHIGAN |
| Event Country | -- |
| Zipcode of the event site | 49701 |
| Event Date Year | 2013 |
| Event Date Month | 8 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 454604N |
| Event Location Longitude | 0844405W |
| Event Location Airport | N/A |
| Event Location Nearest Airport ID | -- |
| Indicates whether the acc/inc occurred off or on an airport | -- |
| 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 | Dusk |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | Thin Broken |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 20 |
| Air Temperature at event time (in degrees celsius) | 24 |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | 5 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 10 |
| Wind Velocity Indicator | -- |
| 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 | Serious |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 1 |
| Injury Total Serious | 1 |
| Injury Total All | 1 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 32957 |
| NTSB Notification Source | FAA ROC |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Jul 30 2014 3:13PM |
| User who most recently changed record | yeal |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N389BD |
| NTSB Number | CEN13LA524 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | STEMME GMBH & CO |
| Aircraft Model | S10-VT |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 11-066 |
| Certified Max Gross Weight | -- |
| Aircraft Category | Glider |
| 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 | Retractable |
| Aircraft, Type of Last Inspection | Annual |
| Date of Last Inspection | Jul 20 2013 12:00AM |
| Airframe hours since last inspection | -- |
| Airframe Hours | 600 |
| ELT Installed | Unknown |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | 512 HORSES INC |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | WINNETKA |
| Aircraft Owner State | IL |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 60093-2228 |
| Operator is an individual? | No |
| Operator Name | 512 HORSES INC |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | -- |
| Operator City | WINNETKA |
| Operator State | IL |
| Operator Country | USA |
| Operator Zip code | 60093-2228 |
| Operator Code | -- |
| Owner has at least one certificate | None |
| 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) | Personal |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | UGN |
| Departure City | Waukegan |
| Departure State | IL |
| Departure Country | USA |
| Departure Time | 1500 |
| Departure Time Zone | CDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | 5Y1 |
| Destination City | Hessel |
| Destination State | MI |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jul 30 2014 3:14PM |
| User who most recently changed record | yeal |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | N/A |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |