Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
CE-11-49
August 26, 2011
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) informs
registered owners/operators of all Air Tractor, Inc. Models AT-802 and
AT-802A airplanes (under Type Certificate Data Sheet A19SW) of an
airworthiness concern. Specifically, this SAIB provides guidance for
general and detailed inspection and lubrication instructions for the
elevator trim control system.
At this time, this airworthiness concern has not been determined to be
an unsafe condition that would warrant airworthiness directive (AD)
action under Title 14 of the Code of Federal Regulations (14 CFR) part
39.
Background
The Federal Aviation Administration (FAA) received a report of a failed
weld on the elevator trim actuator attach clamp assembly bracket, part
number (P/N) 70857-1, on an Air Tractor Model AT-802 airplane having
approximately 5,000 hours time-in-service (TIS). The failure resulted
in the airplane experiencing an unprompted pitch change during flight.
The failure of the clamp assembly bracket was the result of the
elevator trim system binding due to lack of lubrication of the elevator
trim/boost tab bushings. The AT-802/AT-802A owners manual requires the
elevator trim/boost tab bushings be lubricated every 100 hours TIS.
In response, Air Tractor, Inc. has issued Snow Engineering Co. Service
Letter (SL) #300 to remind owners of the importance of complying with
the recommended inspection and lubrication schedules in the
AT-802/AT-802A owners manual. SL #300 specifies the elevator trim/boost
tab bushings be inspected and lubricated every 100 hours TIS in
accordance with the Air Tractor AT-802/802A owners manual. The SL also
recommends a one-time inspection of the elevator trim actuator clamp
assembly bracket, P/N 70857-1, for cracking in the weld. An improved
replacement clamp assembly bracket, P/N 70857-5, is identified in the
SL. The replacement bracket incorporates a weld on both sides of the
mounting bracket to increase resistance to flexing at the weld
location. If cracks are found in the actuator clamp assembly bracket,
P/N 70857-1, replace the bracket with improved bracket P/N 70857-5
before further flight. The improved bracket P/N 70857-5 is incorporated
in production starting at aircraft serial number 802A-0417.
Recommendations
The FAA recommends you do the actions of Snow Engineering Co. SL #300
as described above, including the procedures and time intervals
included in the SL.
In addition, we recommend that you report any brackets found cracked
during any inspection, to include crack location and size, to the FAA
using the Further Information point of contact listed below. Under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the
Office of Management and Budget (OMB) has approved the information
collection contained in this SAIB, and assigned OMB Control Number
2120-0731.
For Further Information Contact
Werner Koch, Aerospace Engineer, 2601 Meacham Blvd, Fort Worth, TX
76137; phone: (817) 222-5133; fax: (817) 222-5960; e-mail:
werner.g.koch@faa.gov.