Airworthiness Directive · Amendment 39-16676 · Nacelles/pylons
The Boeing Company Model 747-200B, -300, -400, -400D, and -400F Series Airplanes Powered by Pratt and Whitney 4000 or General Electric CF6-80C2 Series Engines
This AD applies to The Boeing Company Model 747-200B, -300, -400, -400D, and -400F series airplanes; certificated in any category; equipped with Pratt and Whitney 4000 or General Electric CF6-80C2 series engines, as identified in Boeing Alert Service Bulletin 747-54A2232, dated April 15, 2010.
We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires an inspection to determine the part number of the mid-pivot access door and to determine if the correct door is installed, and the installation of a marker on the mid- pivot access door, and if necessary, repetitive ultrasonic inspections for cracking of the mid-pivot bolt assembly and eventual replacement of the mid-pivot bolt assembly. This AD was prompted by a report that the left and right access doors of the spring beam mid-pivot bolt assembly for the No. 1 strut were inadvertently installed in the incorrect position during strut modification. We are issuing this AD to detect and correct incorrectly installed mid-pivot bolt assemblies on the spring beam on the outboard struts. Incorrectly installed bolt assemblies could lead to fatigue cracking and consequent fracturing of the mid-pivot bolt assembly, which could lead to loss of the spring beam load path and the possible separation of a strut and engine from the airplane during flight.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Within 24 months after the effective date of this AD, do an inspection to determine if the correct mid-pivot access door is installed, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2232, dated April 15, 2010.
(h) If, during the inspection required by paragraph (g) of this AD, the correct mid-pivot door is found to be installed, before further flight, install a marker on the mid-pivot access door, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2232, dated April 15, 2010.
(i) If, during the inspection required by paragraph (g) of this AD, the correct mid-pivot door is not found to be installed, before further flight, do the actions required by paragraphs (i)(1), (i)(2), and (i)(3) of this AD, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2232, dated April 15, 2010.
(1) Rotate the mid-pivot bolt assembly to the correct orientation and replace the mid-pivot access door with a new or serviceable mid-pivot access door.
(2) Install a marker on the mid-pivot access door.
(3) Do the actions required by paragraph (i)(3)(i) or (i)(3)(ii) of this AD.
(i) (Option 1) Do an ultrasonic inspection for cracking of the mid-pivot bolt assembly.
(A) If no cracking is found, do the actions required by paragraphs (i)(3)(i)(A)(1) and (i)(3)(i)(A)(2) of this AD.
(1) Repeat the ultrasonic inspection for cracking of the mid-pivot bolt assembly thereafter at intervals not to exceed 24 months until the action required by paragraph (i)(3)(i)(A)(2) of this AD is done.
(2) Within 60 months after the effective date of this AD, replace the mid-pivot bolt assembly with a new mid-pivot bolt assembly. Replacement terminates the repetitive inspections required by paragraph (i)(3)(i)(A)(1) of this AD.
(B) If any cracking is found, replace the mid-pivot bolt assembly with a new mid-pivot bolt assembly, before further flight.
(ii) (Option 2) Replace the mid-pivot bolt assembly with a new mid-pivot bolt assembly.
