Twin Commander Aircraft has issued a Maintenance Alert calling for inspection and, if necessary, replacement of the elevator bobweight support arms on 690D (Model 900) and 695A and B (Model 1000) Twin Commanders.
The bobweight inspection is to occur at the next 150-hour aircraft inspection and every 150 hours thereafter. The inspection focuses on the area where the bobweight is attached to the support arm. Cracks have been found in that area on an affected aircraft.
The bobweight assembly is located beneath the baggage compartment floor. Its function is to provide consistent elevator control force at all airspeeds.
The procedure detailed in the Maintenance Alert calls for inspection of the support arms at the weight attachment point as well as the hardware associated with the attachment (the 530534-501 arm and the 530546-501 channel attachment to the 530535-1 collars and 530542-1 shaft), for cracks and/or loose fasteners or other damage. If cracks are found, the 530534-501 arm and the 530546-501 channel must be replaced with a new 530534-501 arm and 530546-503 channel. The 530546-503 channel has been lengthened to nest with the 530534-501 arm for the full length, providing better structural arrangement at the weight attachment point.
If loose fasteners or any other damage are found at the collars and shaft attach points, contact Twin Commander Aircraft.
The inspection must be performed even if the arms have been previously replaced, and results of the inspection should be reported to Twin Commander Aircraft.