Source: https://www.federalregister.gov/documents/2003/05/29/03-13388/airworthiness-directives-boeing-model-747-series-airplanes-equipped-with-pratt-and-whitney-jt9d-3-or
Timestamp: 2017-09-25 12:27:42
Document Index: 738264388

Matched Legal Cases: ['art 1', 'art 2', 'art 3', 'art 1', 'art 2', 'arts 1', 'art 2']

Differences Between Alert Service Bulletin and Proposed AD
https://www.federalregister.gov/d/03-13388 https://www.federalregister.gov/d/03-13388
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Boeing Model 747 series airplanes equipped with Pratt & Whitney JT9D-3 or JT9D-7 series engines (except JT9D-70 series engines). This proposal would require detailed inspections of the upper and lower surface of the forward lower spar of the nacelle strut for cracking or other damage, and for any loose or damaged fasteners. This proposal would also require replacement of loose or damaged fasteners and, if necessary, associated repair of the forward lower spar. This action is necessary to detect and correct cracking or other damage to the upper or lower surface of the forward lower spar and any loose or damaged fasteners, which could result in reduced structural capability of nacelle struts one through four, and possible separation of a strut and engine from the airplane during flight. This action is intended to address the identified unsafe condition.
Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-27-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2002-NM-27-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.
Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2002-NM-27-AD.” The postcard will be date stamped and returned to the commenter.
Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-27-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
The FAA has received reports of multiple loose and damaged fasteners and lower spar web damage of the No. 4 strut on two Boeing Model 747 series airplanes equipped with Pratt & Whitney JT9D-7 engines. This damage was observed at approximately 1,900 and 2,900 flight cycles after incorporation of the strut modification described in Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994. That modification was made mandatory by AD 95-10-16, amendment 39-9233 (60 FR 27008, May 22, 1995). Analysis by Boeing indicates that the loose fasteners were the result of incorrect installation of the fasteners or the collars. Multiple loose fasteners allow out-of-plane web deflection and damage to the lower spar web and fasteners. The resulting damage could cause cracking and the loss of the lower spar. This condition, if not corrected, could result in reduced structural capability of the strut, and possible separation of the strut and engine from the airplane during flight.
The FAA has reviewed and approved Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, including Evaluation Form, which describes procedures for the following actions:
Part 1: A detailed inspection of (a) the upper surface of the forward lower spar for cracking and fretting damage to the web, forward bulkhead channel, and stiffeners; and (b) the fasteners in that area for missing heads, damage, and evidence of looseness, such as cracked or broken sealant and fretting or galling around the collars, nuts, or fastener heads.
Part 2: A detailed inspection of (a) the lower surface of the forward lower spar for cracking and fretting damage to the web, c-channel, chords, and stiffener; and (b) the fasteners in that area for missing heads, damage, and evidence of Start Printed Page 31995looseness, such as cracked or broken sealant and fretting or galling around the collars, nuts, or fastener heads.
Part 3: Corrective action, which includes removing loose or damaged fasteners, examining the fastener holes for damage or cracks using a high frequency eddy current (HFEC) inspection, removing cracks or damage by oversizing the holes, ensuring that all cracks and damage are removed using a follow-up HFEC inspection, reaming the hole to a minimum size, and installing a new fastener.
Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, also specifies that, if damage or cracking is found which cannot be removed by oversizing a hole per the alert service bulletin, the Boeing Company should be contacted for additional instructions.
Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, specifies that the manufacturer is to be contacted for disposition of damage or cracks which cannot be repaired by oversizing a fastener hole per the alert service bulletin. The proposed AD, however, would require such repair to be accomplished per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings.
Another difference involves inspection of the upper surface and the lower surface of the forward lower spar. The alert service bulletin recommends inspection of the upper surface after accumulation of 300 flight cycles since modification of the strut in accordance with AD 95-10-16. Inspection of the lower surface is to be done after accumulation of 1,300 flight cycles since modification. This proposed AD, however, provides that, for airplanes which have accumulated 1,300 or more flight cycles since modification of the strut, the initial inspection may include both the upper surface and the lower surface of the forward lower spar. If no damage is detected, no further action is required by the AD.
There are approximately 366 airplanes of the affected design in the worldwide fleet. The FAA estimates that 115 airplanes of U.S. registry would be affected by this proposed AD, that it would take from 20 to 64 work hours per airplane to accomplish the proposed inspections, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed inspections is estimated to be between $1,200 and $3,840 per airplane.
Boeing: Docket 2002-NM-27-AD.
(a) At the later of the times shown in paragraphs (a)(1) and (a)(2) of this AD: Perform a detailed inspection of the upper surface of the forward lower spar to detect cracks, fretting damage, and any loose or damaged fasteners, in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form.
(1) Within 500 flight cycles, but no sooner than 300 flight cycles, after modification of the strut in accordance with AD 95-10-16, amendment 39-2933.
(2) Within 6 months after the effective date of this AD; or
(b) If the detailed inspection required by paragraph (a) of this AD reveals any crack or fretting damage, or any loose or damaged fastener: Prior to further flight, perform a detailed inspection of the lower surface of the forward lower spar to detect cracks, fretting damage, and any loose or damaged fasteners, in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form.
(c) If the detailed inspection of the upper surface of the forward lower spar required by paragraph (a) of this AD reveals no crack or fretting damage and no loose or damaged fastener: At the later of the times specified in paragraphs (c)(1) and (c)(2) of this AD, repeat the detailed inspection of the upper surface of the forward lower spar and perform a detailed inspection of the lower surface of the forward lower spar, in accordance with Parts 1 and 2, respectively, of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form.
(d) If the detailed inspection of the upper surface of the forward lower spar required by paragraph (a) of this AD reveals no crack or fretting damage, and no loose or damaged fastener: Prior to further flight, the operator may elect to perform a detailed inspection of the lower surface of the forward lower spar to detect cracks, fretting damage, and any loose or damaged fasteners, in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form, provided that the airplane has accumulated at least 1,300 flight cycles since modification of the strut per AD 95-10-16.
(1) If the crack or fretting damage to the upper or lower surface of the forward lower spar falls within the parameters specified in Figure 4 or 5 (as applicable) of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form, and the airplane has accumulated 1,300 flight cycles or more since modification of the strut per AD 95-10-16: Remove any loose or damaged fasteners, repair any cracks or fretting damage to the upper or lower surface of the forward lower spar, and install new fasteners, in accordance with the Accomplishment Instructions of the service bulletin. No further action is required by this AD.
(2) If the crack or fretting damage to the upper or lower surface of the forward lower spar does not fall within the parameters specified in Figure 4 or 5 (as applicable) of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form, or if the airplane has accumulated fewer than 1,300 flight cycles since modification of the strut per AD 95-10-16: Accomplish additional repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved as required by this paragraph, the approval must specifically reference this AD.
[FR Doc. 03-13388 Filed 5-28-03; 8:45 am]