Date & Time:
Nov 26, 2015 at 1828 LT
Type of aircraft:
Boeing 737-300
Operator:
Registration:
XA-UNM
Flight Phase:
Landing (descent or approach)
Flight Type:
Scheduled Revenue Flight
Survivors:
Yes
Schedule:
Cancún – Mexico City
MSN:
24248/1636
YOM:
1988
Flight number:
GMT779
Country:
Mexico
Region:
Central America
Crew on board:
5
Crew fatalities:
0
Pax on board:
139
Pax fatalities:
0
Other fatalities:
0
Total fatalities:
0
Aircraft flight hours:
64171
Aircraft flight cycles:
39245
Circumstances:
The aircraft departed Cancún on a regular schedule flight to Mexico City, carrying 139 passengers and five crew members. The flight was uneventful. Following an unstabilized approach, the aircraft landed on runway 05L at an excessive speed. After touchdown, severe vibrations occurred when the left main gear collapsed after a course of 1,097 metres. The airplane slid for 980 metres before coming to rest. All 144 occupants evacuated safely and the aircraft was damaged beyond repair.
Probable cause:
Fracture of the shimmy damper piston and subsequent retraction of the left leg assembly of the landing gear due to vibrations caused during the landing run, which could not be damped due to wear and play existing between the dynamic parts of the links, fittings and apex joint of the shimmy damper.
The following contributing factors were identified:
- Unstabilized approach,
- Inadequate service to shimmy damper and shock strut,
- Landing with a low rate of descent,
- Wear in the Apex joint due to a play between this and the lower torsion link,
- Landing with high ground speed and low descent rate.
The following contributing factors were identified:
- Unstabilized approach,
- Inadequate service to shimmy damper and shock strut,
- Landing with a low rate of descent,
- Wear in the Apex joint due to a play between this and the lower torsion link,
- Landing with high ground speed and low descent rate.
Final Report:
XA-UNM.pdf7.67 MB
