Airworthiness Directive · Amendment 39-18534 · Powerplant
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 and Whitney engines, as identified in Boeing Special Attention Service Bulletin 777-71-0055, Revision 1, dated April 15, 2015.
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 doing the following actions on the left strut and right strut: A one-time cleaning of certain forward strut drain lines; installing new forward strut drain lines and insulation blankets; a leak check of the forward strut drain lines; and repair if any leak is found. This AD also requires revising the maintenance or inspection program, as applicable, to incorporate a certain airworthiness limitation. We are issuing this AD to prevent blockage of forward strut drain lines. This condition 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.
Within 4,000 flight cycles or 750 days after the effective date of this AD, whichever occurs later: Accomplish the actions specified in paragraphs (g)(1) through (g)(4) of this AD on 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 accomplish the revision specified in paragraph (g)(5) of this AD.
(1) Disconnect and remove the forward strut drain lines.
(2) Clean the left system 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 leak is found.
(5) Revise the maintenance or inspection program, as applicable, to incorporate Airworthiness Limitation 54-AWL-01, “Forward Strut Drain Line” as specified in Section D.4, Pratt and Whitney Forward Strut Drain Line, dated March 2014, of the Boeing 777 Maintenance Planning Data (MPD) Document Section 9, Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), D622W001-9, dated 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 (g)(1) through (g)(4) of this AD.
After accomplishing the revision required by paragraph (g)(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 (k) of this AD.
(1) Accomplishing the actions required by paragraph (g) of this AD terminates the actions required by paragraph (g) of AD 2015-17-13 at the modified area only.
(2) Accomplishing the actions specified in paragraphs (i)(2)(i) and (i)(2)(ii) of this AD terminates the inspections required by paragraph (g) of AD 2014-20-10 at the modified area only, provided the actions are accomplished concurrently, or the actions specified in paragraph (i)(2)(ii) of this AD are done after accomplishing the actions specified in paragraph (i)(2)(i) of this AD.
(i) The actions specified in paragraphs (g)(1) through (g)(4) of this AD on the left and right struts are done in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 777-71-0055, Revision 1, dated April 15, 2015; and the revision specified in paragraph (g)(5) of this AD is done.
(ii) A one-time general visual inspection for hydraulic fluid contamination (including contamination caused by hydraulic fluid in its liquid, vapor, and/or solid (coked) form) of the interior of the strut forward dry bay, and all applicable related investigative and corrective actions (including checking drain lines for blockage due to hydraulic fluid coking, and cleaning or replacing drain lines to allow drainage) are done in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 777-54-0028, Revision 1, dated December 10, 2013, except where Boeing Special Attention Service Bulletin 777-54-0028, Revision 1, dated December 10, 2013, specifies to contact Boeing for repair, the repair must be done using a method approved in accordance with the procedures specified in paragraph (k) 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
