AD 2013-03-19 Airworthiness Directives; The Boeing Company Airplanes

Models named: 707-100 long body, -200, -100B long body, -100B short body series, 707-300, -300B, -300C, -400 series, 720, 720B series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to The Boeing Company Model 707-100 long body, -200, -100B long body, and -100B short body series airplanes; Model 707-300, -300B, -300C, and -400 series airplanes; and Model 720 and 720B series airplanes; certificated in any category; line numbers 1 through 941 inclusive.

Comply with this AD within the compliance times specified, unless already done.

This paragraph restates the requirements of paragraph (a) of AD 2001-17-20, Amendment 39-12411 (66 FR 44954, August 27, 2001). Within 1 year or 4,000 flight hours after October 1, 2001 (the effective date of AD 2001-17-20), whichever occurs first: Replace the wiring for the fuel boost pumps and override pumps, install Teflon sleeving over the wiring, and do all associated actions, per the Accomplishment Instructions of Boeing Service Bulletin A3500, Revision 1, dated April 26, 2001. The associated actions include performing a general visual inspection of the area around each fuel boost pump and override pump for evidence of a fuel leak; finding the source of any fuel leak and repairing the affected area; replacing the conduit, if required; and performing a detailed visual inspection of the wiring installed in the conduit for evidence of electrical arcing or a fuel leak, or exposed copper wire. If replacement of the conduit is deferred per the Accomplishment Instructions of Boeing Service Bulletin A3500, Revision 1, dated April 26, 2001, repeat the inspection for fuel leaks every 500 flight hours until the conduit is replaced, and replace the conduit within 6,000 flight hours or 18 months, whichever occurs first. (1) For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light, and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.” (2) For the purposes of this AD, a detailed visual inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

This AD was prompted by a report that, while investigating a fuel leak around the bolts on the number 1 fuel boost pump on a Boeing Model 707 series airplane, an operator found wire damage where the fuel boost pump wiring exited the boost pump and entered the boost pump access area. We are issuing this AD to detect and correct damaged wiring for the fuel boost pumps and override pumps, which could cause electrical arcing that could puncture the conduit containing the wire, and result in a fuel tank explosion or a fire adjacent to the fuel tank.

This AD supersedes AD 2001-17-20, Amendment 39-12411 (66 FR 44954, August 27, 2001).