20th of April 2018, Gear Failure, Blog #700
- V2Aviation
- 23 minutes ago
- 2 min read
A 25-year-old McDonnell Douglas MD-83 was opererating a charter flight 7 years ago. With a crew of seven and 94 passengers the flight originated from Chicago-O'Hare International Airport (IL, USA) and had Alexandria International Airport (LA, USA) as its destination.
The flight had progressed since engine start without any difficulties and was vectored for a visual approach and landing on runway 14 (9352 ft long) at Alexandria International Airport. The weather at the time was good;
Wind - 310 at 5 knots
Visibility - 10 miles
Clouds - None
Temperature - 18°C
Dewpoint - 5°C
Altimeter 30.26 inHg (1025 hPa)
The approach was flown at the correct speed and descent rate for the actual landing weight and the aircraft touched down normaly on runway 14.
After landing, the right main landing gear (RMLG) cylinder fractured and collapsed
aft and the airplane settled onto the right wing and flaps. The aircraft came to a stop approximatey 7000 feet from the apporach end of the runway where the crew called for an evacuation due to a suspected fire on the right wing. The left-hand forward door slide did not deploy during the opening of the door, all passengers and crew evacuated through the remaing doors. There were no injuries. The aircraft sustained substantial damaged and was written off.
Damage was found at;
Wing tip - Impact and abbrasion damage
Outboard slat
Right outboard lower wing skin
Right outboard flap and flap hinges
RH Main Landing gear had failed rearwward in to the right inboard flap and the right hand wing to body fairing
The damaged wingtip and outboard wing (source aviatiom-safety.net © R. Maddern)
An investigation was launched by the National Transportation Safety Board in to the accident. The following observations were made.
The escape slide at the left forward door did not deploy or inflate due to the depletion of the gas charge in the reservoir. The reservoir depleted due to
a leak in the valve assembly and was not caught during multiple inspections since installation of the slide assembly in the airplane.
The landing gear cylinder fractured under normal landing loads due to the
presence of a fatigue crack on the forward side of the cylinder in an area subject to an AD inspection for cracks. The most recent AD inspection of the cylinder was performed 218 landings prior when the fatigue crack was large enough to be detectable. A previous AD inspection performed 497 landings prior to the accident also did not detect the crack that would have been marginally detectable at the time.
The National Transportation Safety Board determined that the probable cause(s) of this accident was;
The failure of the right main landing gear under normal loads due to fatigue cracking in an area subject to an FAA Airworthiness Directive that was not adequately inspected.
The NTSB Aviation Investigation Final Report, which served as a source for this blog, can be accessed by clicking on the .pdf below. It contains an extensive discription of the analysis of the fatigue crack in the landing gear.