AD 59-08-02

59-08-02 BOEING: Applies to all Model 707-100 Series Aircraft with Bendix Flux Gate Compass system. Compliance required as indicated. Reports have indicated that excessive indicator errors can be introduced in the Bendix remote compass system when it is in the slaving mode and when the aircraft is exposed to wing oscillations resulting from rough air, spoiler operation, etc. As an interim safety measure pending further investigation and development by the manufacturer of an improved Bendix flux valve installation, the following aircraft operating limitation is required for all aircraft incorporating the Bendix system: Whenever heading information is required by the pilots, the two Bendix systems (two RMI and two CDI indicators) should be frequently checked against each other and against the magnetic standby compass to detect obvious errors in indication. This information must be included, within the next 10 hours' flight time, on a placard adjacent to the RMI and CDI indicators until an approved Airplane Flight Manual revision covering this subject is available. The foregoing limitation does not apply to aircraft in which the magnetic sensing device (flux gate) is installed in the fuselage body by the manufacturer or installed in accordance with Boeing 707 Service Bulletin No. 587 "Bendix Compass System Flux Gate Relocation," which describes a satisfactory and approved means of mounting the flux valves.