Airworthiness Directive · Amendment 39-19433 · Nacelles/pylons
The Boeing Company Airplanes
This AD applies to all The Boeing Company Model 707-100 Long Body, -200, -100B Long Body, and -100B Short Body series airplanes; Model 707-300, -300B, -300C, and -400 series airplanes; and Model 720 and 720B series airplanes; certificated in any category.
We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 707, 720, and 720B series airplanes. This AD was prompted by a report indicating that a fracture of the midspar fitting resulted in the separation of the inboard strut and engine from the airplane, and a determination that existing inspections are not sufficient for timely detection of cracking. This AD requires repetitive inspections of certain nacelle strut spar and overwing fittings, and diagonal braces and associated fittings; replacement of the diagonal brace assembly on certain airplanes; and applicable related investigative and corrective actions. We are issuing this AD to address the unsafe condition on these products.
Prior to the accumulation of 3,500 total flight hours; within 700 flight hours after the most recent inspection specified in Boeing 707 Alert Service Bulletin A3514, dated July 29, 2004, was done; or within three months after the effective date of this AD; whichever occurs later: Do a detailed inspection for cracking of the front spar fittings at nacelle struts numbers 1, 2, 3, and 4, in accordance with the Accomplishment Instructions of Boeing 707 Alert Service Bulletin A3514, Revision 1, dated November 9, 2016. If any cracking is found, before further flight, replace the affected fitting, in accordance with the Accomplishment Instructions of Boeing 707 Alert Service Bulletin A3514, Revision 1, dated November 9, 2016. Repeat the inspections thereafter at intervals not to exceed 700 flight hours.
Within 1,500 flight cycles or 48 months after the most recent detailed inspection required by paragraph (g) of this AD was done, whichever occurs first, do a surface HFEC inspection for cracking of the aft lugs on the front spar fittings at nacelle struts numbers 1, 2, 3, and 4, and do all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing 707 Alert Service Bulletin A3514, Revision 1, dated November 9, 2016, except as required by paragraph (l)(4) of this AD. Do all applicable corrective actions before further flight. Repeat the inspection thereafter at intervals not to exceed 1,500 flight cycles or 48 months, whichever occurs first.
At the times specified in paragraph 1.E., “Compliance,” of Boeing 707 Alert Service Bulletin A3365, Revision 3, dated March 9, 2017, except as required by paragraph (l)(1) of this AD: Do the inspections specified in paragraphs (i)(1) through (i)(3) of this AD and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing 707 Alert Service Bulletin A3365, Revision 3, dated March 9, 2017, except as required by paragraph (l)(3) of this AD. Do all applicable related investigative and corrective actions before further flight. Repeat the inspections thereafter at the applicable time specified in paragraph 1.E., “Compliance,” of Boeing 707 Alert Service Bulletin A3365, Revision 3, dated March 9, 2017.
(1) Do a detailed inspection for any crack at all five holes in the overwing support fitting, and at the flange radii.
(2) Do the inspection specified in paragraph (i)(2)(i) or (i)(2)(ii) of this AD.
(i) Do a surface HFEC inspection for any crack in the overwing support fitting around the hole immediately forward of the spar chord, with the bolt in place, and at the flange radii.
(ii) Do an open hole HFEC inspection for any crack in the overwing support fitting at the hole immediately forward of the spar chord.
(3) Do the inspection specified in paragraph (i)(3)(i) or (i)(3)(ii) of this AD.
(i) Do an ultrasonic inspection for any crack in the overwing support fitting around the four holes common to the fitting and the spar chord, with the bolts in place.
(ii) Do a surface HFEC inspection for any crack in the overwing support fitting around the four holes common to the fitting and the spar chord, with the bolts in place.
For airplanes with nacelle strut diagonal braces and associated fittings which have accumulated 7,500 flight cycles or more: At the applicable times specified in paragraph 1.E., “Compliance” of Boeing 707 Alert Service Bulletin A3364, Revision 4, dated February 21, 2017, except as required by paragraph (l)(2) of this AD, do the inspections specified in paragraphs (j)(1) through (j)(3) of this AD. Repeat the inspections thereafter at the applicable intervals specified in tables 1, 2, 3, and 4 of paragraph 1.E., “Compliance,” of Boeing 707 Alert Service Bulletin A3364, Revision 4, dated February 21, 2017. If any crack is found during any inspection required by this paragraph, before further flight, do all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing 707 Alert Service Bulletin A3364, Revision 4, dated February 21, 2017, except as required by paragraph (l)(3) of this AD.
(1) Do a detailed inspection of the nacelle strut diagonal brace end fittings, diagonal brace tube, forward mating fitting, and aft mating fitting for any crack.
(2) Do HFEC inspections of the nacelle strut diagonal brace end fittings, forward mating fitting, and aft mating fitting for any crack. As an alternative for the aft mating fitting, do a dye penetrant inspection of vertical webs on aft mating fitting for any crack.
(3) Do an HFEC inspection of the diagonal brace tube for any crack.
For Group 3, 4, and 6 airplanes as identified in Boeing 707 Alert Service Bulletin A3364, Revision 4, dated February 21, 2017, on which the outboard diagonal brace end fitting (forward or aft) attach holes have been oversized as specified in Boeing 707 Alert Service Bulletin A3364, Revision 3, dated May 29, 1981: Within 1,000 flight cycles after the effective date of this AD, replace the diagonal brace assembly, in accordance with Figure 3 of Boeing 707 Alert Service Bulletin A3364, Revision 4, dated February 21, 2017.
(1) For purposes of determining compliance with the requirements of this AD: Where Boeing 707 Alert Service Bulletin A3365, Revision 3, dated March 9, 2017, uses the phrase “the Revision 3 date of this service bulletin,” this AD requires using “the effective date of this AD.”
(2) For purposes of determining compliance with the requirements of this AD: Where Boeing 707 Alert Service Bulletin A3364, Revision 4, dated February 21, 2017, uses the phrase “the Revision 4 date of this service bulletin,” this AD requires using “the effective date of this AD.”
(3) Where Boeing 707 Alert Service Bulletin A3364, Revision 4, dated February 21, 2017; and Boeing 707 Alert Service Bulletin A3365, Revision 3, dated March 9, 2017; specify contacting Boeing: This AD requires repair using a method approved in accordance with the procedures specified in paragraph (o) of this AD.
(4) Where Boeing 707 Alert Service Bulletin A3514, Revision 1, dated November 9, 2016, specifies contacting Boeing for replacement instructions: This AD requires replacement using a method approved in accordance with the procedures specified in paragraph (o) of this AD.
(1) Accomplishing the initial inspections required by paragraph (j) of this AD terminates all requirements of AD 82-24-03.
(2) Accomplishing the initial inspections required by paragraph (g) of this AD, terminates all requirements of AD 2005-08-15.
