Source: https://www.federalregister.gov/documents/2007/08/23/E7-16656/airworthiness-directives-boeing-model-737-200c-series-airplanes
Timestamp: 2018-08-21 22:11:16
Document Index: 523725091

Matched Legal Cases: ['art 4', 'art 25', 'art 25', 'art 91', 'art 91', 'art 121', 'art 125', 'art 135', 'arts 121']

Docket No. FAA-2007-29029
Directorate Identifier 2007-NM-175-AD
https://www.federalregister.gov/d/E7-16656 https://www.federalregister.gov/d/E7-16656
Start Preamble Start Printed Page 48243
The FAA proposes to adopt a new airworthiness directive (AD) for all Boeing Model 737-200C series airplanes. This proposed AD would require revising the FAA-approved maintenance inspection program to include inspections that will give no less than the required damage tolerance rating for each structural significant item (SSI), doing repetitive inspections to detect cracks of all SSIs, and repairing cracked structure. This proposed AD results from a report of incidents involving fatigue cracking and corrosion in transport category airplanes that are approaching or have exceeded their design service objective. We are proposing this AD to maintain the continued structural integrity of the entire fleet of Model 737-200C series airplanes.
We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “FAA-2007-29029; Directorate Identifier 2007-NM-175-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.
As a follow-on from that determination, we issued AC No. 91-56, “Supplemental Structural Inspection Program for Large Transport Category Airplanes,” dated May 6, 1981. That AC provides guidance material to manufacturers and operators for use in developing a continuing structural integrity program to ensure safe operation of older airplanes throughout their operational lives. This guidance material applies to transport airplanes that were certified under the fail-safe requirements of part 4b (“Airplane Airworthiness, Transport Categories”) of the Civil Air Regulations or damage tolerance structural requirements of part 25 (“Airworthiness Standards: Transport Category Airplanes”) of the Federal Aviation Regulations (FAR) (14 CFR part 25), and that have a maximum gross weight greater than 75,000 pounds. The procedures set forth in that AC are applicable to transport category airplanes operated under subpart D (“Special Flight Operations”) of part 91 of the FAR (14 CFR part 91); part 121 (“Operating Requirements: Domestic, Flag, and Supplemental Operations”); Start Printed Page 48244part 125 (“Certification and Operations: Airplanes having a Seating Capacity of 20 or More Passengers or a Maximum Payload of 6,000 Pounds or More”); and part 135 (“Operating Requirements: Commuter and On-Demand Operations”) of the FAR (14 CFR parts 121, 125, and 135). The objective of the SSIP was to establish inspection programs to ensure timely detection of fatigue cracking.
In order to evaluate the effect of increased fatigue cracking with respect to maintaining fail-safe design and damage tolerance of the structure of Boeing Model 737-200C series airplanes, Boeing conducted a structural reassessment of those airplanes, using damage tolerance evaluation techniques. Boeing accomplished this reassessment using the criteria contained in AC No. 91-56, as well as Amendment 25-45 of section 25.571 (“Damage-tolerance and fatigue evaluation of structure”) of the FAR (14 CFR 25.571). During the reassessment, members of the airline industry participated with Boeing in working group sessions and developed the SSIP for Model 737-200C series airplanes. Engineers and maintenance specialists from the FAA also supported these sessions. Subsequently, based on the working group's recommendations, Boeing developed the Supplemental Structural Inspection Document (SSID).
We previously issued AD 98-11-04 R1, amendment 39-10984 (64 FR 987, January 7, 1999), applicable to all Boeing Model 737-100, -200, and -200C series airplanes (which refers to Boeing Document No. D6-37089, “Supplemental Structural Inspection Document” (SSID), Revision D, dated June 1995, as the appropriate source of service information for doing the required actions). That AD requires the FAA-approved maintenance inspection program be revised to include inspections that will give no less than the required damage tolerance rating (DTR) for each structural significant item (SSI), and repair of cracked structure. The affected SSIs include, but are not limited to, the wing, fuselage, empennage, and strut. For Model 737-200C series airplanes, that AD requires inspecting SSIs affected by cargo configuration changes only. For Model 737-100 and -200 series airplanes, that AD requires inspecting all affected SSIs.
We have reviewed Boeing Document No. D6-37089, “Supplemental Structural Inspection Document for Model 737-100/200/200C Airplanes,” Revision E, dated May 2007 (hereafter “Revision E”). Revision E describes procedures for revising the FAA-approved maintenance inspection program to include inspections that will give no less than the required damage tolerance rating (DTR) for each SSI, doing repetitive inspections to detect cracks of all SSIs, and repairing cracked structure. The inspections specified in Revision E are essentially identical to those in Revision D. The applicability of Revision E has been updated, among other editorial changes, to show that for the Model 737-200C, SSIs not affected by cargo configuration changes are subject to the same inspections as Model 737-100 and -200 series airplanes. Accomplishing the actions specified in Revision E is intended to adequately address the unsafe condition.
Paragraph (g) of the proposed AD would require incorporation of a revision into the FAA-approved maintenance inspection program that provides no less than the required DTR for each SSI listed in Revision E.
Accomplishing the actions required by paragraphs (g) and (h) of this AD ends the requirements of AD 98-11-04 R1 for Model 737-200C series airplanes only. Operators of Model 737-100 and -200 series airplanes must continue to do the actions required by AD 98-11-04 R1.
For Model 737-200C series airplanes, Section 3.0, “Structural Significant Items (SSIs),” of Revision E specifies a threshold of 66,000 or 46,000 flight cycles for accomplishing the initial inspections, depending on the airplane configuration; however, it does not specify a grace period for airplanes that are near or have passed that threshold. This proposed AD would allow a grace period of 12 months after the effective date of the AD to incorporate Revision E into the FAA-approved maintenance inspection program. This proposed AD also would allow a grace period of 4,000 flight cycles measured from 12 months after the effective date of the AD to initiate the applicable inspections to detect cracks of all SSIs.
There are about 49 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.
Revision of maintenance inspection program 1,000, per operator (3 U.S. operators) $80 $80,000 per operator 9 $240,000.
Inspections 500 per airplane 80 $40,000, per airplane, per inspection cycle 9 $360,000, per inspection cycle.
Further, compliance with this proposed AD would be a means of compliance with the aging airplane safety final rule (AASFR) for the baseline structure of Model 737-200C series airplanes. The AASFR final rule requires certain operators to incorporate damage tolerance inspections into their maintenance inspection programs. These requirements are described in 14 CFR 121.370(a) and 129.16. Accomplishment of the actions required by this proposed AD will meet the requirements of these CFR sections for the baseline structure. The costs for accomplishing the inspection portion of this proposed AD were accounted for in the regulatory evaluation of the AASFR final rule.
Boeing: Docket No. FAA-2007-29029; Directorate Identifier 2007-NM-175-AD.
(b) Accomplishing the actions required by paragraph (g) and the initial inspections required by paragraph (h) of this AD ends the requirements of AD 98-11-04 R1, amendment 39-10984, for Model 737-200C series airplanes only. Operators of Model 737-100 and -200 series airplanes must continue to do the actions required by AD 98-11-04 R1.
(d) This AD results from a report of incidents involving fatigue cracking and corrosion in transport category airplanes that are approaching or have exceeded their design service objective. We are issuing this AD to maintain the continued structural integrity of the entire fleet of Model 737-200C series airplanes.
(g) At the applicable time specified in Table 1 of this AD, incorporate a revision into the FAA-approved maintenance inspection program that provides no less than the required damage tolerance rating (DTR) for each structural significant item (SSI) listed in Revision E. (The required DTR value for each SSI is listed in Revision E.) The revision to the maintenance inspection program must include and must be implemented in accordance with the procedures in Section 5.0, “Damage Tolerance Rating (DTR) System Application,” and Section 6.0, “SSI Discrepancy Reporting” of Revision E. Under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has approved the information collection requirements contained in this AD and has assigned OMB Control Number 2120-0056.Start Printed Page 48246
Table 1.—Compliance Time for Revising Maintenance Inspection Program
For airplanes with SSIs—
(1) Affected by the cargo configuration Before the accumulation of 46,000 total flight cycles, or within 12 months after the effective date of this AD, whichever occurs later.
(2) Not affected by the cargo configuration Before the accumulation of 66,000 total flight cycles, or within 12 months after the effective date of this AD, whichever occurs later.
(h) At the applicable time specified in Table 2 of this AD, do the applicable initial inspections to detect cracks of all SSIs, in accordance with Revision E. Repeat the applicable inspections thereafter at the intervals specified in Section 3.0, “Implementation” of Revision E.
Table 2.—Compliance Time for Initial Inspections
(1) Affected by the cargo configuration Before the accumulation of 46,000 total flight cycles, or within 4,000 flight cycles measured from 12 months after the effective date of this AD, whichever occurs later.
(2) Not affected by the cargo configuration Before the accumulation of 66,000 total flight cycles, or within 4,000 flight cycles measured from 12 months after the effective date of this AD, whichever occurs later.
(k)(1) The Manager, Seattle Aircraft Certification Office (ACO) has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.
[FR Doc. E7-16656 Filed 8-22-07; 8:45 am]