Accident Cessna 172K N7370G,
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ASN Wikibase Occurrence # 284804
 
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Date:Thursday 7 June 2007
Time:09:30 LT
Type:Silhouette image of generic C172 model; specific model in this crash may look slightly different    
Cessna 172K
Owner/operator:Dale Miller Independant Consultants
Registration: N7370G
MSN: 17259070
Year of manufacture:1970
Total airframe hrs:4369 hours
Engine model:Teledyne Continental IO-360
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Amarillo, Texas -   United States of America
Phase: Unknown
Nature:Training
Departure airport:Memphis, TX (F21)
Destination airport:Amarillo-Tradewind Airport, TX (TDW/KTDW)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The student pilot lost control of the airplane after the left main landing gear spring failed during the landing roll. According to the 45-hour student pilot, while attempting a crosswind landing in a single-engine airplane, the right main landing gear tire touched down first, followed by the left main landing gear tire; however, when the left hand tire made contact with the ground "something went wrong." The student pilot thought he may have had a flat tire and he held the left wing up for as long as possible to minimize the amount of weight on the tire. The airplane went-off the side of the runway after the student pilot was unable to maintain directional control of the airplane. Examination of the airplane revealed the left main landing gear spring fractured into two sections at the point where the foot-step attached to the spring. The fractured spring assembly, including the foot-step and bracket, were shipped to a metallurgical laboratory for further examination. According to the Factual Report, the spring gear fractured at the point where the foot-step was installed to the spring. The step was welded to the spring gear by two transverse weld beads on the top and side of the spring. In addition, there were two longitudinal weld beads on the lower surface of the spring. According to the report, "...the weld beads were tall and rounded with weld spatter on the surrounding surfaces and not consistent with good quality workmanship." The spring gear fracture intersected the longitudinal weld on the lower surface of the spring. A magnified examination of the fracture surface revealed that the fracture initiated at this weld bead. The airplane's last annual inspection was completed in January 2007. A review of the maintenance logbooks revealed no entries relating to a weld repair on the spring gear. According to the owner, who just recently purchased the airplane, no maintenance had been performed on the airplane since it was purchased. According to the manufacturer's Service Manual, the foot-step should be bonded to the steel landing gear spring with EA9303 or a similar adhesive. In addition, FAA Advisory Circular AC43.13-1B CHG 1, Acceptable Methods, Techniques, and Practices-Aircraft inspection and Repair, section 4-89, titled Aircraft Parts Not To Be Welded, part (A), stated, "Do not weld alloy steel parts such as aircraft bolts, turnbuckle ends, etc., which have been heat treated to improve their mechanical properties."


Probable Cause: The failure of the left main landing gear spring assembly as a result of an unapproved repair by an unknown person(s), which resulted in a loss of directional control during the landing roll.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: DFW07LA130
Status: Investigation completed
Duration: 2 months
Download report: Final report

Sources:

NTSB DFW07LA130

Revision history:

Date/timeContributorUpdates
01-Oct-2022 09:00 ASN Update Bot Added

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