United Airline From Hong Kong, joined Jan 2001, 8792 posts, RR: 17 Posted (12 years 3 weeks 6 days 1 hour ago) and read 1196 times:
Nation: FAA orders emergency inspection for new Boeing jets
The Associated Press
SEATTLE (April 25, 2001 11:22 a.m. EDT http://www.nandotimes.com) - Government officials have issued an emergency order for checks of a control mechanism on more than 800 new-model Boeing 737s, an order prompted by reports of problems from three operators.
The Federal Aviation Administration issued an emergency airworthiness directive Tuesday, giving airlines 10 days to inspect the jam nut on the backup elevator tab assembly on the tail of the plane and make repairs as needed.
A service bulletin was issued Monday by Boeing. The FAA action makes the checks mandatory for U.S. operators.
Lou Cancelmi, a spokesman for Alaska Airlines, said the job involves a visual inspection that should take about 10 minutes and, if necessary, about an hour to tighten the nut.
The elevator assembly, installed on 817 Boeing 737 600s, -700s and -800s worldwide, including 380 in the United States, controls the up and down movement of the nose of the plane.
At least three carriers have found the nuts were improperly installed or inadequately tightened, raising a risk of loss of control in flight, the FAA directive said.
The assembly was the subject of a separate airworthiness directive last month which cited excessive vibrations caused by missing parts or too much wear.
Boeing officials said the problem apparently stems from adjustments that were made to some plane's backup elevator controls during flight tests before the planes were delivered to buyers.
Sandy Angers, a Boeing spokeswoman, said records are being checked to determine how many of the planes covered by the directive may have had backup elevator controls adjusted before delivery.
Elevators are the movable control surfaces on the horizontal stabilizer, which resembles a small wing at the rear of the plane.
Elevator tab control rods, part of a backup for the hydraulic system normally used by pilots to move the elevators, would be used only if both the primary and secondary hydraulic system failed.
The three operators found damage from small jam nuts that may not have been tightened correctly, raising a risk of damage to a tab control rod. Damage to both rods could result in excessive free play in the control mechanism, causing elevator tab flutter, the FAA said.
"This condition, if not corrected, could result in loss of controllability of the airplane," the agency said.