Airworthiness Directive · Amendment 39-16937 · Engine exhaust
The Boeing Company Airplanes
This AD applies to all The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes, certificated in any category.
We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. This AD was prompted by a report that the top 3 inches of the aero/fire seals of the blocker doors on the thrust reverser torque boxes are not fireproof. This AD requires a one-time inspection to determine the part numbers of the aero/fire seals of the blocker doors on the thrust reverser torque boxes on the engines, and replacing affected aero/fire seals with new, improved aero/fire seals. We are issuing this AD to prevent a fire in the fan compartment (a fire zone) from migrating through the seal to a flammable fluid in the thrust reverser actuator compartment (a flammable fluid leakage zone), which could result in an uncontrolled fire.
For airplanes having an original airworthiness certificate issued before the effective date of this AD, and for airplanes on which the date of issuance of the original export certificate of airworthiness is before the effective date of this AD: Within 60 months or 8,200 flight cycles, whichever occurs first, after the effective date of this AD, perform a one-time detailed inspection to determine the color of the aero/fire seals of the blocker doors on the thrust reverser torque boxes on the engines. For any aero/fire seal having a completely grey color (which is the color of seals with part number (P/N) 315A2245-1 or 315A2245-2), with no red at the upper end of the seal, do the actions specified in paragraph (i) of this AD. For any aero/fire seal having a red color at the upper end of the seal (which indicates installation of seals with P/N 315A2245-7 or 315A2245-8), no further action is required by this AD. A review of airplane maintenance records is acceptable in lieu of this inspection if from that review the part number of the correct aero/fire seals (P/N 315A2245-7 or 315A2245-8) can be conclusively determined to be installed.
For the purposes of this AD, a detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirrors, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”
For any aero/fire seal identified during the inspection/records check required by paragraph (g) of this AD to have a non-fireproof seal: Within six months after doing the actions required by paragraph (g) of this AD, replace the aero/fire seals of the blocker doors on the thrust reverser torque boxes on the engines with new, improved aero/fire seals, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-78-1074, Revision 1, dated September 15, 2005. Replacing the aero/fire seals of the blocker doors on the thrust reverser torque boxes on the engines with new, improved aero/fire seals, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-78-1074, Revision 1, dated September 15, 2005, is terminating action for the inspection required by paragraph (g) of this AD.
As of the effective date of this AD, no person may install a non-fireproof thrust reverser seal having P/N 315A2245-1 or P/N 315A2245-2 on any airplane.
Replacements done before the effective date of this AD in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-78-1074, dated April 7, 2005, are acceptable for compliance with the requirements of paragraph (i) of this AD.
