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20040810019009I

Incident · Minor damage
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FAA incident report · Dhav DHC6300 · Grand Canyon, AZ · August 10, 2004

FAA Aviation Safety Information Portal

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Date
August 10, 2004 · 15:20 local
Place
Grand Canyon, AZ
Airport
Grand Canyon National Park
Phase of flight
Level Off Touchdown
Operating rules
Air carrier (Part 121)
Operator
OEZA
Damage
Minor damage
Aircraft
N147SA
Reported as
Dhav DHC6300
People aboard
21
Fatal injuries
0
Pilot’s flight hours
8,009 total1,094 in this make and model130 in the last 90 days

From the FAA’s Accident/Incident Data System (AIDS), through its Aviation Safety Information Portal, as reported. The NTSB investigates accidents separately, and its record of an accident is the fuller one. The aircraft is matched to the registry by N-number and event date, checked against the reported make and model; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

What happened

The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.

(-23) While landing at gcn, the aircraft veered to the left and departed the runway. The aircraft then struck a runway edge light with the nose gear and a frangible taxiway sign with the right main landing gear. Witnesses who observed the aircraft on final, stated that the nose gear appeared to be turned nearly 90 degrees to the direction of flight. Inspection of the nose tire at the scene revealed cupping that appeared to be nearly 90 degrees to the direction of landing. The swerve made by the aircraft was hard enough to roll the right main tire off of its rim causing it to deflate. It appears that this incident was the result of three interrelated issues. The maintenance of the nose wheel steering centering device and indicator; the design of the nose wheel steering system; and inadequate pilot operating procedures. After recovering the aircraft, the operator discovered that with the cockpit nose wheel steering indicator aligned, the nose wheel steering collar did not quite align with the centering tang which prevented the nose wheel from locking in the centered position while airborne. While it was confirmed that the clearances in the system were within tolerance, when combined,in this case, they apparently prevented the nose wheel from being locked in the centered position. The operator has revised their inspection and maintenance procedures in an effort to maintain tighter tolerances within the nose wheel steering system. Regarding design of the nose wheel steering system, the handle is in close proximity to the yoke and appears capable of being accidentally bumped. This would cause an unlatched nose wheel to move from a centered position as on the incident aircraft. Finally, the operator lacked a procedure that would ensure that the nose wheel was, in fact, centered and latched. This incident has been resolved by the publication of a new pilot procedure to be accomplished both after take-off and before landing. The procedure is to move the nose wheel steering lever up and down in order to feel that the nose gear had mechanically locked into the center position.

As the FAA filed it

(-23) WHILE LANDING AT GCN, THE AIRCRAFT VEERED TO THE LEFT AND DEPARTED THE RUNWAY. THE AIRCRAFT THEN STRUCK A RUNWAY EDGE LIGHT WITH THE NOSE GEAR AND A FRANGIBLE TAXIWAY SIGN WITH THE RIGHT MAIN LANDING GEAR. WITNESSES WHO OBSERVED THE AIRCRAFT ON FINAL, STATED THAT THE NOSE GEAR APPEARED TO BE TURNED NEARLY 90 DEGREES TO THE DIRECTION OF FLIGHT. INSPECTION OF THE NOSE TIRE AT THE SCENE REVEALED CUPPING THAT APPEARED TO BE NEARLY 90 DEGREES TO THE DIRECTION OF LANDING. THE SWERVE MADE BY THE AIRCRAFT WAS HARD ENOUGH TO ROLL THE RIGHT MAIN TIRE OFF OF ITS RIM CAUSING IT TO DEFLATE. IT APPEARS THAT THIS INCIDENT WAS THE RESULT OF THREE INTERRELATED ISSUES. THE MAINTENANCE OF THE NOSE WHEEL STEERING CENTERING DEVICE AND INDICATOR; THE DESIGN OF THE NOSE WHEEL STEERING SYSTEM; AND INADEQUATE PILOT OPERATING PROCEDURES. AFTER RECOVERING THE AIRCRAFT, THE OPERATOR DISCOVERED THAT WITH THE COCKPIT NOSE WHEEL STEERING INDICATOR ALIGNED, THE NOSE WHEEL STEERING COLLAR DID NOT QUITE ALIGN WITH THE CENTERING TANG WHICH PREVENTED THE NOSE WHEEL FROM LOCKING IN THE CENTERED POSITION WHILE AIRBORNE. WHILE IT WAS CONFIRMED THAT THE CLEARANCES IN THE SYSTEM WERE WITHIN TOLERANCE, WHEN COMBINED,IN THIS CASE, THEY APPARENTLY PREVENTED THE NOSE WHEEL FROM BEING LOCKED IN THE CENTERED POSITION. THE OPERATOR HAS REVISED THEIR INSPECTION AND MAINTENANCE PROCEDURES IN AN EFFORT TO MAINTAIN TIGHTER TOLERANCES WITHIN THE NOSE WHEEL STEERING SYSTEM. REGARDING DESIGN OF THE NOSE WHEEL STEERING SYSTEM, THE HANDLE IS IN CLOSE PROXIMITY TO THE YOKE AND APPEARS CAPABLE OF BEING ACCIDENTALLY BUMPED. THIS WOULD CAUSE AN UNLATCHED NOSE WHEEL TO MOVE FROM A CENTERED POSITION AS ON THE INCIDENT AIRCRAFT. FINALLY, THE OPERATOR LACKED A PROCEDURE THAT WOULD ENSURE THAT THE NOSE WHEEL WAS, IN FACT, CENTERED AND LATCHED. THIS INCIDENT HAS BEEN RESOLVED BY THE PUBLICATION OF A NEW PILOT PROCEDURE TO BE ACCOMPLISHED BOTH AFTER TAKE-OFF AND BEFORE LANDING. THE PROCEDURE IS TO MOVE THE NOSE WHEEL STEERING LEVER UP AND DOWN IN ORDER TO FEEL THAT THE NOSE GEAR HAD MECHANICALLY LOCKED INTO THE CENTER POSITION.