Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
Excessive wear and tear of the backlash remover mechanism has been found several times on Goodrich Part Number (P/N) 23400-3B and P/N 23400-7 elevator booster control units (BCU), while corrosion has been found on some components in other BCU. The wear and tear may result in a (partly) blocked operation of the elevator system in the normal (hydraulic) mode, while any corrosion may result in deteriorated elevator control when the BCU is in MANUAL mode. * * * * * The unsafe condition is wear and tear, and corrosion of the backlash remover mechanism, which can cause a (partly) blocked operation of the elevator system in the normal (hydraulic) mode and deteriorated elevator control when the BCU is in MANUAL mode, which could result in loss of control of the airplane. The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.