Document
OAS-25 (4/18)
Department of the Interior Aviation
SAFETY ALERT
No. DOI SA 25-03 July 25, 2025 Page 1 of 2 Subject: Top Cub Rear Flight Control Stick Cover Installation Area of Concern: Flight Controls Distribution: All Top Cub Activities Discussion: Recently, a CC18-180 Top Cub pilot discovered that the rear control stick cover was improperly installed, interfering with the full control movement of the front stick. The pilot experienced scraping sounds and resistance during the preflight control checks ( SAFECOM #25-0738 ) . The rear cover was installed over the control stick stub in an uneven manner due to a leather floor boot that should have been removed prior to installation. This resulted in the rear stick stub contacting the inside of the cover (Figure 1). The CubCrafters AFM/POH Supplement 9.15 contains the proper installation instructions. Additionally, other Top Cub inspections revealed that some rear covers were installed incorrectly with various non-standard or unapproved hardware and floorboard holes. In one instance, the inside of the cover had metal scrape marks indicating where the rear stick stub grinded during previous flight operations similar to this event.
Figure 1. (Left) Proper Rear Stick cover installation. (Right) Scrape marks on the inside cover due to improper installation.
A recent mishap ( DOI LL 25-02 Improper Installation of Flight Controls and DOI Aviation Safety Alert 25- 01 Top Cub Rear Flight Control Stick Installation ) revealed the hazards associated with the improper No. DOI SA 25-03 Date: July 25, 2025 Page 2 of 2 installation of the aft seat control stick in the Top Cub aircraft. These publications emphasized proper rear stick and cover installation instructions and the importance of proper flight control checks before flight.
The CubCrafters Rear Control Stick Cover is installed over the rear stick stub to prevent the stick stub from inadvertent movement by cargo or a passenger, to prevent the flight controls from becoming jammed by cargo sliding forward, and to prevent foreign objects from falling into the rear flight control mechanisms and the belly of the aircraft. The manufacturer’s installation instructions for the Rear Control Stick Cover Kit are available at CubCrafters.com, Service Letter SL0005 Rev A CubCrafters SL0005 - Rear Stick Cover Installation Rev A . The subsequent removal and reinstallation instructions are available in the CC18 AFM/POH Supplement 9.15. (page 9-15-2) TC10000AFM_Rev_U_-_Statement.pdf.
As a result of these recent findings, the following recommendations are provided to prevent this situation from occurring and to ensure flight safety. All Top Cub Pilots and mechanics should: 1. Review the AFM Supplements Section 9.15 concerning proper rear stick removal and cover installation. Ensure that the front control stick can move through the full range of motion (include trim and flaps) and there is no contact between the rear stick stub and the stick cover.
2. Ensure both preflight and before takeoff checklists requiring flight control checks are performed correctly IAW the AFM to verify free and clear maximum range of travel.
3. Flight Control Checks . It is recommended to perform full flight control checks during the pre-flight inspection so that any unusual sounds may be heard.
a. Check free and correct motion (flight controls are moving up, down, left, and right as they should). Many pilots use a box pattern for this check. It’s important to check each corner of “the box” rather than a “cursory sweep”.
b. Ensure no unusual force is required for movement (this means either abnormal pressure or excessive loose play).
c. Listen for unusual sounds from cables, linkages, and pulleys.
4. Ensure the Rear Control Stick Cover is installed when the rear stick is removed. The only time the rear leather floor boot and stick should be installed is during instruction with a qualified flight instructor. For all other operations require the Rear Control Stick Cover to be installed.
/s/ Keith C. Raley Keith C. Raley Chief, Aviation Safety, Training, Program Evaluation, and Quality Management DOI, Office of Aviation Services