Airworthiness Directive · Amendment 39-18246 · Nacelles/pylons
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 777-200 and -300 series airplanes, certificated in any category, equipped with Pratt & Whitney engines, as identified in Boeing Special Attention Service Bulletin 777-54-0027, Revision 1, dated September 12, 2013.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 777-200 and -300 series airplanes equipped with Pratt and Whitney engines. This AD was prompted by reports of blocked drain lines at the engine forward strut that caused flammable fluid to accumulate in a flammable leakage zone. This AD requires repetitive functional checks for blockage of the forward strut drain line and doing corrective actions if necessary, and a one-time cleaning of certain forward strut drain lines. This AD also provides an optional replacement of the drain lines and installation of insulation blankets, and a revision of the maintenance or inspection program, as applicable, to incorporate a certain airworthiness limitation, which would terminate the repetitive checks of the forward strut drain line. We are issuing this AD to detect and correct blockage of forward strut drain lines, which could cause flammable fluids to collect in the forward strut area and potentially cause an uncontrolled fire or cause failure of engine attachment structure and consequent airplane loss.
At the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Special Attention Service Bulletin 777-54-0027, Revision 1, dated September 12, 2013, except as provided by paragraph (h) of this AD, do the actions specified in paragraphs (g)(1) and (g)(2) of this AD, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 777-54-0027, Revision 1, dated September 12, 2013. Repeat the functional check required by paragraph (g)(1) of this AD, thereafter at the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Special Attention Service Bulletin 777-54-0027, Revision 1, dated September 12, 2013, until the terminating action specified in paragraph (i) of this AD is done.
(1) Do a functional check for blockage of the forward strut drain line of the left and right strut and do all applicable corrective actions (including cleaning or replacing blocked drain tubes, repairing fluid leaks, and cleaning the inlet drain screen on the right system disconnect assembly inlet). Do all applicable corrective actions before further flight. Alternate tee fitting part numbers BACT16BR120612JN and AS4139J120612 may be used during the replacement of the forward strut drain lines, provided the installation is performed in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 777-54-0027, Revision 1, dated September 12, 2013.
(2) Do a one-time cleaning of the smaller forward strut drain lines connected to the left systems disconnect, the strut forward lower spar, and the forward fire seal pan inlets.
Where Boeing Special Attention Service Bulletin 777-54-0027, Revision 1, dated September 12, 2013, refers to a compliance time “after the Revision 1 date of this Service Bulletin,” this AD requires compliance within the specified compliance time after the effective date of this AD.
Accomplishment of the actions specified in paragraphs (i)(1) through (i)(4) of this AD, for both the left and right struts, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 777-71-0055, Revision 1, dated April 15, 2015, and accomplishment of the revision specified in paragraph (i)(5) of this AD, terminates the repetitive functional checks required by paragraph (g)(1) of this AD at the modified area only.
(1) Disconnect and remove the forward strut drain lines.
(2) Clean the left systems disconnect, the strut forward lower spar, and the forward fireseal pan drain lines.
(3) Install new forward strut drain lines and insulation blankets.
(4) Do a leak check of the forward strut drain lines, for any leak, and repair if any leaking is found.
(5) Revise the maintenance or inspection program, as applicable, to incorporate Airworthiness Limitation 54-AWL-01, “Forward Strut Drain Line”, Section D.4, Pratt and Whitney Forward Strut Drain Line, of the Boeing 777 Maintenance Planning Data (MPD) Document Section 9, Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), D622W001-9, Revision October 2014. The initial compliance time for Airworthiness Limitation 54-AWL-01 is within 2,000 flight cycles or 1,500 days, whichever occurs first, after doing the actions specified in paragraphs (i)(1) through (i)(4) of this AD.
After accomplishing the revision required by paragraph (i)(5) of this AD, no alternative actions (e.g., inspections) or intervals may be used unless the actions or intervals are approved as an alternative method of compliance (AMOC) in accordance with the procedures specified in paragraph (l) of this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
