An FAA Special Airworthiness Information Bulletin released on Nov. 27 warns of potential problems with the Boeing Company Model 737-100, -200, -300, -400, and -500 aircraft. 737 owners and operators were advised to inspect the wire bundle W138 and add protection sleeves to the wire bundles for the equipment cooling blowers.

The bulletin was released after a report that an operator experienced the illumination of the entire fire-warning panel.

The left wing overheat light also illuminated. The crew reported that they were unable to silence the bell or extinguish the blinking lights. On the ground, maintenance found a significant section of wire bundle W138 behind the E3-4 shelf in the Electronic Equipment Bay completely burned away. The burned wires were a result of wire insulation damage caused by an electrical arc when the wires rubbed against the clamps on the cooling blowers.

For more information, contact Binh V. Tran, Aerospace Engineer, FAA Seattle Aircraft Certification Office, 1601 Lind Avenue, SW, Renton, WA 98055-4056; phone: (425) 917-6485.