Airworthiness Directive · Amendment 39-15956 · Boeing Model 777 Airplanes
Boeing Model 777 Airplanes
This AD applies to all Boeing Model 777 airplanes, certificated in any category.
The FAA is superseding an existing airworthiness directive (AD), which applies to all Boeing Model 777 airplanes. That AD currently requires, for the drive mechanism of the horizontal stabilizer, repetitive detailed inspections for discrepancies, repetitive lubrication of the ballnut and ballscrew, repetitive measurements of the freeplay between the ballnut and the ballscrew, and corrective action if necessary. This new AD revises the compliance times of the existing AD. This AD results from a report of extensive corrosion of a ballscrew in the drive mechanism of the horizontal stabilizer on a Boeing Model 757 airplane, which is similar in design to the ballscrew on Model 777 airplanes. We are issuing this AD to prevent an undetected failure of the primary load path for the ballscrew in the drive mechanism of the horizontal stabilizer and subsequent wear and failure of the secondary load path, which could lead to loss of control of the horizontal stabilizer and consequent loss of control of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
For airplanes that have received an original airworthiness certificate or original export certificate of airworthiness prior to the effective date of this AD: Within 180 days or 3,500 flight hours after the effective date of this AD, whichever occurs first, perform a maintenance records check or inspect to determine the status of the horizontal stabilizer trim actuator (HSTA) as specified in paragraph (f)(1), (f)(2), (f)(3), or (f)(4) of this AD, as applicable:
(1) The original HSTA delivered with the airplane has not been removed and is still installed on the airplane;
(2) The original HSTA has been replaced with an HSTA in a known serviceable condition;
(3) The original HSTA has been replaced with an HSTA that is not in a known serviceable condition, and which has not received a detailed inspection and freeplay measurement as described in paragraphs (g) and (h) of this AD since that replacement; or
(4) The original HSTA has been replaced with an HSTA that is not in a known serviceable condition, and which has received a detailed inspection and freeplay measurement as described in paragraphs (g) and (h) of this AD since that replacement.
Note 1: The phrase “known serviceable condition” is defined in section 3.A., Note 6, of Boeing Service Bulletin 777-27A0059, Revision 2, dated January 15, 2009.
Within the compliance times specified in paragraphs (g)(1), (g)(2), (g)(3), and (g)(4) of this AD, as applicable: Perform a detailed inspection for discrepancies of the horizontal stabilizer trim actuator ballnut and ballscrew, in accordance with Part 1 of the Accomplishment Instructions of Boeing Service Bulletin 777-27A0059, Revision 2, dated January 15, 2009. Repeat the detailed inspection thereafter at intervals not to exceed 3,500 flight hours or 12 months, whichever occurs first. If any discrepancy is found during any inspection required by this AD, before further flight, replace the actuator with an actuator in a known serviceable condition, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 777-27A0059, Revision 2, dated January 15, 2009.
(1) For airplanes identified in paragraph (f)(1) of this AD: Before the accumulation of 15,000 total flight hours, or within 18 months after the effective date of this AD, whichever occurs later.
(2) For airplanes identified in paragraph (f)(2) or (f)(4) of this AD: Before the accumulation of 15,000 flight hours since the replacement of the HSTA, or within 18 months after the effective date of this AD, whichever occurs later.
(3) For airplanes identified in paragraph (f)(3) of this AD: Before the accumulation of 3,500 flight hours since the replacement of the HSTA, or within 12 months after the effective date of this AD, whichever occurs later.
(4) For airplanes that have received an original airworthiness certificate or original export certificate of airworthiness on or after the effective date of this AD: Before the accumulation of 15,000 total flight hours, or within 18 months after the issuance of the original airworthiness certificate or original export certificate of airworthiness, whichever occurs later.
Within the compliance times specified in paragraphs (h)(1), (h)(2), (h)(3), and (h)(4) of this AD, as applicable: Perform a freeplay measurement of the ballnut and ballscrew in accordance with Part 2 of the Accomplishment Instructions of Boeing Service Bulletin 777-27A0059, Revision 2, dated January 15, 2009. Repeat the freeplay measurement thereafter at intervals not to exceed 18,000 flight hours or 60 months, whichever occurs first. If the freeplay is found to exceed the limits specified in the service bulletin during any measurement required by this AD, before further flight, replace the actuator with an actuator in a known serviceable condition, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 777-27A0059, Revision 2, dated January 15, 2009.
(1) For airplanes identified in paragraph (f)(1) of this AD: Before the accumulation of 15,000 total flight hours, or within 18 months after the effective date of this AD, whichever occurs later.
(2) For airplanes identified in paragraph (f)(2) or (f)(4) of this AD: Before the accumulation of 15,000 flight hours since the replacement of the HSTA, or within 18 months after the effective date of this AD, whichever occurs later.
(3) For airplanes identified in paragraph (f)(3) of this AD: Before the accumulation of 3,500 flight hours since the replacement of the HSTA, or within 12 months after the effective date of this AD, whichever occurs later.
(4) For airplanes that have received an original airworthiness certificate or original export certificate of airworthiness on or after the effective date of this AD: Before the accumulation of 15,000 total flight hours, or within 18 months after the issuance of the original airworthiness certificate or original export certificate of airworthiness, whichever occurs later.
(i) Within the compliance times specified in paragraphs (i)(1), (i)(2), (i)(3), and (i)(4) of this AD, as applicable: Lubricate the ballnut and ballscrew in accordance with Part 3 of the Accomplishment Instructions of Boeing Service Bulletin 777-27A0059, Revision 2, dated January 15, 2009. Repeat the lubrication thereafter at intervals not to exceed 2,000 flight hours or 12 months, whichever occurs first.
(1) For airplanes identified in paragraph (f)(1) of this AD: Before the accumulation of 15,000 total flight hours, or within 18 months after the effective date of this AD, whichever occurs later.
(2) For airplanes identified in paragraph (f)(2) or (f)(4) of this AD: Before the accumulation of 15,000 flight hours since the replacement of the HSTA, or within 18 months after the effective date of this AD, whichever occurs later.
(3) For airplanes identified in paragraph (f)(3) of this AD: Before the accumulation of 3,500 flight hours since the replacement of the HSTA, or within 12 months after the effective date of this AD, whichever occurs later.
(4) For airplanes that have received an original airworthiness certificate or original export certificate of airworthiness on or after the effective date of this AD: Before the accumulation of 15,000 total flight hours, or within 18 months after the issuance of the original airworthiness certificate or original export certificate of airworthiness, whichever occurs later.
Actions performed prior to the effective date of this AD, in accordance with Boeing Alert Service Bulletin 777-27A0059, dated September 18, 2003; or Boeing Alert Service Bulletin 777-27A0059, Revision 1, dated August 18, 2005; are considered acceptable for compliance with the corresponding actions specified in paragraphs (g), (h), and (i) of this AD.
Any HSTA overhauled within the compliance times specified in paragraphs (g), (h), and (i) of this AD or before the effective date of this AD—as part of a “hard-time” replacement program that includes removal of the HSTA from the airplane and overhaul of the stabilizer ballscrew in accordance with original equipment manufacturer component maintenance manual instructions—meets the intent of one detailed inspection, one freeplay inspection, and one lubrication of the HSTA. Therefore, any such HSTA is considered acceptable for compliance with the initial accomplishment of the actions specified in paragraphs (g), (h), and (i) of this AD, and repetitions of those actions may be determined from the performance date of that overhaul.
As of the effective date of this AD, no person may install, on any airplane, a horizontal stabilizer trim actuator that is not in a “known serviceable condition” as defined in Note 6, section 3.A., of Boeing Alert Service Bulletin 777-27A0059, Revision 2, dated January 15, 2009; unless a detailed inspection, freeplay measurement, and lubrication of that actuator are performed in accordance with paragraphs (g), (h), and (i) of this AD, as applicable.
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
