Fuel Hose Installation and Electrical Wiring in Aircraft AD2009-15-01

I was blown away by this Airworthiness Directive 2009-15-01 on HAWKER BEECHCRAFT CORPORATION G36 "the next generation Bonanza". To quote:

This AD results from reports of chafing between the wire harness/connector(s) and fuel line. We are issuing this AD to detect and correct chafing between the wire harness/connector(s) and fuel line. This chafing could lead to fuel leaking into the cockpit and fire in the cockpit if wiring arcs through the fuel line. One report indicated arcing from a chafing wire harness burned a hole through the fuel tube.




A fuel line in the cockpit resting against an electrical wire bundle? Makes me shudder in fear!

For all of you building homebuilt aircraft, here is a very safe, simple and sensible standard for installing aircraft hose and electrical wiring:

MIL-W-5088L Wiring, Aerospace Vehicles

Wiring shall be supported independent of and with the maximum practicable separation from all fluid-carrying lines, tubes and equipment.

Where this routing is not practicable, the wiring shall pass below the lines at an angle rather than parallel to the lines.

Wiring shall not be attached to fluld carrying lines, tubes and equipment unless they require electrical connections or their separation is less than two inches, In areas where separation is less than two inches, the wiring shall be installed to maintain positive separation of at least .500 inch. 


There is more in the mil-spec but this about sums it up; don't place a fuel line against an electrical wire bundle. Chafe protection is just a delaying method and does not provide positive and long term protection.