FlarePath
Cases › ERA09IA056 · Part 121 airline

DeHavilland DHC-8-311Piedmont Airlines

Philadelphia, PA, USA · 2008-11-16·N326EN

0
fatal
0
serious
No injury
highest injury
Minor
damage

What happened

NTSB summary, verbatim

The airplane was on approach for landing. When the landing gear was selected to the extended position, the main landing gear extended properly but the nose landing gear did not. The crew performed a go-around, exited the airport airspace, and unsuccessfully attempted to extend the nose landing gear using several checklists and in consult with ground-based maintenance personnel. A subsequent fly-by of the air traffic control tower confirmed that the nose landing gear doors were open, but that the nose landing gear was not extended. The captain subsequently landed the airplane with the nose landing gear retracted and delayed lowering the nose until the slowest speed possible. The nose of the airplane contacted the runway and the airplane slid for about 525 feet before it stopped. There was no fire, and the passengers deplaned normally at the scene. On-site examination of the airplane and a laboratory examination of the nosegear components revealed that the steering links had been circumferentially loaded in tension beyond their load-carrying capacity. Failure of the steering links allowed the nosewheels to rotate in the wheel well and become wedged within the structure. Hardness testing satisfied the manufacturer's minimum requirements and no determination could be made as to when the overload occurred.

Photographs

1the aircraft, and what the investigators found
The aircraft before the accident
CLT 5-9-08 N326EN (2492285655)
James Willamor from Raleigh, NC, USA · CC BY-SA 2.0 · Wikimedia Commons

Probable cause

the Board's determination
The mechanical overload of the nosewheel steering links for undetermined reasons, which resulted in nose landing gear rotation and its subsequent wedging within the wheel well structure.

Occurrence sequence

2 stepsNTSB coding · CICTT taxonomy
  1. 1 · Landing
    Abnormal runway contact
  2. 2 · Approach
    Sys/Comp malf/fail (non-power)
    defining event

Findings

1 causal · 1 contributing
  • CAUSE
    Aircraft › Aircraft systems › Landing gear system › Gear extension and retract sys — Capability exceeded
  • FACTOR
    Aircraft › Aircraft systems › Landing gear system › Nose/tail landing gear — Malfunction

Sequence of events

8 timed eventsfrom the FDR factual report · claude-sonnet-5
  1. 550,530 sec (SRN)Departurep.3
    The aircraft departed
  2. 551,517 sec (SRN)Approachp.3
    The aircraft began an initial descent to PHL
  3. 551,670 sec (SRN)Go-around 1p.4
    Power was applied to both engines and a climb was initiated to go around
  4. 553,080 sec (SRN)Approachp.4
    The aircraft begins a second descent to PHL
  5. 553,460 sec (SRN)Go-around 2p.4
    Power was applied to both engines and a climb is initiated to go around
  6. 554,910 sec (SRN)Final Approachp.4
    The aircraft began its final descent to PHL
  7. 555,835 to 555,876 sec (SRN)Landingp.4
    The aircraft landed and decelerated at PHL; a precise time of landing could not be determined based on available FDR parameters
  8. 555,880 sec (SRN)Post-landingp.4
    The engine shutdown process began

NTSB analysis

from the final report

The airplane was on approach for landing. When the landing gear was selected to the extended position, the main landing gear extended properly but the nose landing gear did not. The crew performed a go-around, exited the airport airspace, and unsuccessfully attempted to extend the nose landing gear using several checklists and in consult with ground-based maintenance personnel. A subsequent fly-by of the air traffic control tower confirmed that the nose landing gear doors were open, but that the nose landing gear was not extended. The captain subsequently landed the airplane with the nose landing gear retracted and delayed lowering the nose until the slowest speed possible. The nose of the airplane contacted the runway and the airplane slid for about 525 feet before it stopped. There was no fire, and the passengers deplaned normally at the scene. On-site examination of the airplane and a laboratory examination of the nosegear components revealed that the steering links had been circumferentially loaded in tension beyond their load-carrying capacity. Failure of the steering links allowed the nosewheels to rotate in the wheel well and become wedged within the structure. Hardness testing satisfied the manufacturer's minimum requirements and no determination could be made as to when the overload occurred.