Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD would require adding diodes to the fuel cross-feed wiring, and revising the airplane flight manual to include procedures to use when the left or right generator is selected OFF. This proposed AD was prompted by a false cross-feed command to the right-hand fuel control card, due to the cross-feed inputs on the left- and right-hand fuel control cards being connected together and causing an imbalance of fuel between the left and right wing tanks. We are proposing this AD to prevent lateral imbalance of the airplane, which can be corrected by deflecting the aileron trim, but which increases the pilot's workload. Uncontrolled fuel cross-feed results in lateral imbalance that could exceed the airplane's limitation in a short period of time. Exceeding the lateral imbalance limit could result in reduced control of the airplane.