Maule M7 N969AW

Summary

On 11 September 2018 at about 21:37 local time, a Maule M7 registered N969AW was involved in an accident near Floresville, Texas, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 September 2018 at 21:37

Classification

Accident

Location

Floresville, Texas, United States

Nearest airport

Private (N/A)

Coordinates

29.1297, -98.7500

Aircraft

Maule M7

Registration

N969AW

Category

Airplane

Year built

2003

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Floresville → Floresville

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA18LA270

Nobody was injured.

The separation of the left inboard main landing gear (MLG) attachment bolt due to insufficient torque, which resulted in the collapse of the left MLG.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The flight instructor and the private pilot-rated student, who was in the left seat and was also the airplane owner, were practicing approaches. Upon landing, the pilots heard a loud popping noise, and the instructor then initiated a go-around. Subsequently, the pilot felt vibration under the floorboard. The pilots thought that a tire might have blown. The instructor flew the approach and conducted a three-point landing, and just before the airplane came to a stop, the left main landing gear (MLG) collapsed, which resulted in substantial damage to the left wing. An examination of the left MLG revealed that its inboard attachment bolt and nut were missing. After the accident, the bolt was found along the path of the landing rollout. Examination of the attachment bolt revealed that the bolt threads were undamaged. The attachment nut was not found. The right MLG's inboard attachment bolt and nut were found still attached; however, they were loose, with only two to three threads visible past the nut.   The inboard attachment bolts were upgraded high-strength bolts. The airframe manufacturer had issued a service letter (SL) that stated that, when using the high-strength bolts, the outboard attachment bolts required the same amount of torque as indicated in the airplane maintenance manual but that the inboard attachment bolts required a higher torque amount than the standard bolts. However, a review of the maintenance manual revealed that it did not include the new, higher torque requirements specified in the SL. Therefore, mechanics who only follow the maintenance manual may not be aware that higher torque values are required.   A review of the airplane maintenance records revealed that its last annual inspection was completed about 6 months before the accident. The mechanic who performed the inspection reported that he did not verify the torque on the bolts, that he only used his hands to confirm that they were secure, and that he did not reference the SL during the inspection. It could not be determined whether the mechanic's failure to verify the torque on the bolts or the insufficient torque values in the MM led to the torque on the left inboard MLG attachment bolt being insufficient and the resultant collapse of the left MLG.

Quoted verbatim from the NTSB record.