SPECIAL AIRWORTHINESS INFORMATION BULLETIN
Aircraft Certification Service
Washington, DC
U.S. Department of Transportation
Federal Aviation Administration
CE-08-02

November 2, 2007

This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) is to inform you of an airworthiness concern on Cessna 180, 182, and 185 series airplanes (serial numbers listed in Table 1).

Background

A pilot operating a Cessna 185 reported to maintenance personnel of having the horizontal stabilizer trim “freeze up in flight” (i.e. jam due to mechanical wear). Maintenance personnel inspected the system and found the trim screw barrels in the tail to be excessively worn (Cessna Part Number (P/N) 0712500-13). One of the barrels was stripped out and the second barrel had approximately one-third of the threads missing. The screws that thread into the barrels (Cessna P/N 0712500-11) also were worn. Eight similar occurrences have been reported in service difficulty reports.

Cessna created temporary revisions for the service manuals listed in Table 1 to add a scheduled inspection of the free play in the horizontal stabilizer. This inspection will identify if excessive wear exists in the horizontal stabilizer screw-jack actuator threads and if the actuator needs to be repaired or replaced. This inspection supplements the maintenance manual requirement to inspect moveable parts for excessive wear and is recommended to be completed every 1,000 hours.

Excessively worn threads in the pitch trim actuator could lead to failure of the pitch trim control in flight and make the aircraft difficult to control.

Table 1
Manual Number Affected Aircraft Years
D138-1-13 Model 180 All Serial Numbers
Model 185 All Serial Numbers
Model 182 Serial Numbers 33000 thru 53007 and 18253008 through 18253598		 1953-1962
D637-1-13 Model 180 All Serial Numbers
Model 185 All Serial Numbers		 1963-1968
D2000-9-13
Model 180 All Serial Numbers
Model 185 All Serial Numbers
 1969-1980
D2067-1-13 Model 180 All Serial Numbers
Model 185 All Serial Numbers		 1981-1985
 
At this time, this airworthiness concern is not an unsafe condition that would warrant AD action under Title 14 of the Code of Federal Aviation Regulations (14 CFR) part 39.

Recommendations

The FAA recommends that owners and operators of aircraft listed in Table 1 complete the new inspection for excessive free play in the temporary revision to the maintenance manual.

For Further Information Contact:

David Fairback, Mechanical Aerospace Engineer, 1801 Airport Road – Room 100, Wichita, KS 67209; phone: 316-946-4154; fax: 316-046-4107