Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
CE-13-27 R1
January 5, 2022
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) is intended to
remind owners and operators of any airplane with cable-driven flight
controls of the importance of adhering to existing inspection
procedures in the applicable maintenance or shop manuals.
The FAA is issuing this revision to list additional models with characteristics similar to those originally listed.
At this time, the airworthiness concern is not 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 FAA recently received a report of a failed flap extend cable. The
failure occurred on approach when the flaps were deployed to 45
degrees. The sudden retraction of the right flap caused the airplane to
roll about 80 degrees to the right. The pilot was unable to retract the
left flap, but was able to maintain control with the assistance of a
passenger, divert to another airport, and land safely by utilizing
almost full left aileron control. The report stated the cable was
original (over 4,800 flight hours), and the most recent 100-hour
inspection had been completed approximately 10 flight hours prior to
cable failure.
A search of the FAA’s service difficulty report (SDR) system revealed
numerous events of a similar nature over a 20 year period. Most reports
of fraying occurred near pulleys, and some included comments such as
“failure occurred behind a pulley and is not easily inspected without
the use of a mirror.” If the cable is not properly inspected, it can
appear to be acceptable when it really is not. This SAIB focuses on the
condition of the flap extend cables as they route around pulleys on all
Textron Aviation, Inc. (formerly Cessna) 310, 310A, 310B, 310C, 310D,
310E, 310F, 310G, 310H, 310I, 310J, 310J-1, 310K, 310L, 310N, 310P,
310Q, 310R, 320, 320-1, 320A, 320B, 320C, 320D, 320E, 320F, 321, 335,
336, 337, 337A, 337B, 337C, 337D, 337E, 337F, 337G, 337H, 340, 340A,
401, 401A, 401B, 402, 402A, 402B, 402C, 411, 411A, 414, 414A, 421,
421A, 421B, 421C, and 425 airplanes. However, it also applies to the
entire flight control system on any airplane model with cable-driven
flight controls.
Inadequate inspection of the flight control cables may result in
undetected wear and/or corrosion that could lead to cable failure.
Recommendations
The FAA recommends the following:
Follow the existing
maintenance manual instructions and inspection intervals. For the
Textron Aviation airplanes listed above, this typically is a visual
inspection of each flight control cable every 200 hours or 12 months,
and an expanded inspection of each flight control cable every 600
hours. These intervals may vary slightly depending on model and use of
the airplane, so please reference the appropriate airplane maintenance
manual.
For both the visual and
expanded inspections, operate the flight controls through their full
travel so that all portions of the cable are exposed for inspection.
This may require one person to cycle the controls and a second person
to inspect the cables. If this is not possible, maintenance personnel
may find it necessary to remove the cable to get access to the entire
length of the cable.
For maintenance personnel, review AC 43.13-1B, Chapter 7, paragraph 7-149., “Cable System Inspection.”