Monday, November 11, 2019

Part(s) Separation from Aircraft: Maule M-7-235C Orion, N969AW; accident occurred September 11, 2018 in Floresville, Wilson County, Texas

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; San Antonio, Texas

Aviation Accident Factual Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:

Location: Floresville, TX
Accident Number: ERA18LA270
Date & Time: 09/11/2018, 1637 CDT
Registration: N969AW
Aircraft: Maule M7
Aircraft Damage: Substantial
Defining Event: Part(s) separation from AC
Injuries: 2 None
Flight Conducted Under: Part 91: General Aviation - Instructional 

On September 11, 2018, about 1637 central daylight time, a Maule M-7-235C, N969AW, was substantially damaged after the left, main landing gear collapsed at a private, grass airstrip near Floresville, Texas. The flight instructor and a private pilot-rated student were not injured. The airplane was operated by an individual under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight that originated at Floresville about 1600.

According to an inspector with the Federal Aviation Administration (FAA), the flight instructor and his student were practicing approaches. Upon landing, the pilots heard a loud popping noise, and the flight instructor performed a go-around. The student in the left seat could feel vibration under the floor board. Suspecting a blown tire, the pilots discussed how the airplane might handle during the next landing. The instructor flew the approach and landing. After a normal 3-point landing, and just before the airplane came to a stop, the left main landing gear collapsed.

The FAA inspector responded to the accident site and examined the wreckage. He reported that the left wing sustained structural damage during the landing. The propeller struck the ground after the gear collapsed. The inspector observed that the left main landing gear inboard attachment bolt was missing. The bolt was later found along the path of the landing rollout. The bolt threads were undamaged, and the attaching nut was not located. The right inboard attachment bolt and nut were still attached; however, they were untorqued and loose, with only 2-3 threads visible past the nut.

The 100-hr/annual inspection procedures in the M7-235C Maintenance Manual (MM) stated that, under the main landing gear inspection procedures, "The torque on the inboard attach bolts must be 240-300 inch pounds and on outboard clamp bolts 160-190 inch pounds." The airplane was fitted with upgraded high strength attach bolts. Maule Service Letter (SL) No. 66, revision B, dated May 2, 2006, addressed the installation of the high strength bolts. According to the SL, the torque for the outboard clamp bolts was the same as the MM inspection guide (160-190 inch pounds); however, the torque for the inboard attach bolts increased to 450-500 inch pounds. Service Letter No. 66 also stated, "Retorque bolts after 25 hours and per Maintenance Manual thereafter." The MM did not incorporate the new torque requirements for the inboard bolts. Following the MM only, this allowed the inboard bolts to be torqued to 240-300 inch pounds, or about 200 inch pounds lower than the requirement in SL No. 66.

A review of the aircraft maintenance records revealed that the most recent annual inspection was completed in April, 2018. The mechanic who performed the inspection reported that he did not retorque the attachment bolts; he checked them by feeling them with his hands only. He did not reference SL No. 66 during the annual inspection.

Flight Instructor Information

Certificate: Flight Instructor; Commercial
Age: 31, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land
Seat Occupied: Right
Other Aircraft Rating(s): None
Restraint Used: Unknown
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): Airplane Multi-engine; Airplane Single-engine; Instrument Airplane
Toxicology Performed: No
Medical Certification: Class 2 With Waivers/Limitations
Last FAA Medical Exam: 12/27/2017
Occupational Pilot: Yes
Last Flight Review or Equivalent:
Flight Time: 5100 hours (Total, all aircraft)

Student Pilot Information

Certificate: Private
Age: 51, Male
Airplane Rating(s): Single-engine Land
Seat Occupied: Left
Other Aircraft Rating(s): None
Restraint Used: Unknown
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 3 Without Waivers/Limitations
Last FAA Medical Exam: 01/19/2018
Occupational Pilot: No
Last Flight Review or Equivalent:
Flight Time: 515 hours (Total, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Make: Maule
Registration: N969AW
Model/Series: M7 235C
Aircraft Category: Airplane
Year of Manufacture:
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: 25093C
Landing Gear Type: Tailwheel
Seats: 4
Date/Type of Last Inspection: 04/30/2018, Annual
Certified Max Gross Wt.: 2500 lbs
Time Since Last Inspection:
Engines: Reciprocating
Airframe Total Time: 1975 Hours at time of accident
Engine Manufacturer: Lycoming
Engine Model/Series: IO-540 Series
Registered Owner: On file
Rated Power: 235
Operator: On file
Operating Certificate(s) Held: None

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: SSF, 577 ft msl
Distance from Accident Site: 20 Nautical Miles
Observation Time: 1653 CDT
Direction from Accident Site: 290°
Lowest Cloud Condition: Scattered / 3300 ft agl
Visibility:  10 Miles
Lowest Ceiling: Broken / 5500 ft agl
Visibility (RVR):
Wind Speed/Gusts: 5 knots /
Turbulence Type Forecast/Actual: None / None
Wind Direction: 360°
Turbulence Severity Forecast/Actual: N/A / N/A
Altimeter Setting: 29.88 inches Hg
Temperature/Dew Point: 28°C / 21°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Floresville, TX (N/A)
Type of Flight Plan Filed: None
Destination: Floresville, TX (N/A)
Type of Clearance: None
Departure Time:  CDT
Type of Airspace: Class G

Airport Information

Airport:Private (N/A) 
Runway Surface Type: Unknown
Airport Elevation: 661 ft
Runway Surface Condition:Unknown
Runway Used: N/A
IFR Approach: None
Runway Length/Width:
VFR Approach/Landing: Full Stop; Traffic Pattern

Wreckage and Impact Information

Crew Injuries: 2 None
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 2 None
Latitude, Longitude: 29.129722, -98.750000 (est)

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