Airworthiness Directives; Boeing Model 727 Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for all Boeing Model 727 airplanes. This proposed AD would require repetitive inspections for cracks of the body skin, doubler, and bear strap at the forward edge of the upper and lower hinge cutouts of the forward entry door, related investigative actions, and corrective action if necessary. This proposed AD also would require a preventive modification. This proposed AD is prompted by reports of skin and bear strap cracks at hinge cutouts. We are proposing this AD to detect and correct cracks in the skin and bear strap at the hinge cutouts of the forward entry door, which could result in rapid decompression of the airplane.

DATES:

We must receive comments on this proposed AD by July 29, 2005.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, Washington, DC 20590.
• By fax: (202) 493-2251.
• Hand Delivery: room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

You may examine the contents of this AD docket on the Internet at http://dms.dot.gov , or at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Daniel F. Kutz, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW. Renton, Washington 98055-4056; telephone (425) 917-6456; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2005-21434; Directorate Identifier 2004-NM-75-AD” in the subject line 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 submitted by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that website, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov .

Examining the Docket

You can examine the AD docket in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

We have received reports from 12 operators of skin cracks in the forward entry door cutouts on 75 Boeing Model 727 airplanes. The cracks were detected or found on airplanes that had accumulated between 19,500 and 65,500 total flight hours, and between 11,700 and 50,600 total flight cycles. The skin cracks were between 0.25 inch and 3.25 inches long and were initiated along the forward edge of the upper and lower hinge cutouts. One operator also reported cracks in the bear strap of the forward entry door. The airplane that had these cracks had accumulated 30,700 total flight hours and 28,100 total flight cycles. According to the manufacturer, the cracks were caused by fatigue, which resulted from cabin pressurization cycles.

Approximately 22% of these 75 airplanes had cracks at only the upper hinge cutout; 43% had cracks at only the lower hinge cutout; and 35% had cracks at both upper and lower hinge cutouts.

In addition, one operator reported cracks in the bear strap that is located in the fastener row directly above and below the hinge cutout on six airplanes. The operator found the cracks after installing a repair or preventative modification on three of the six airplanes.

Cracks in the skin and bear strap at the hinge cutouts of the forward entry door, if not detected and corrected, could result in rapid decompression of the airplane.

Related Rulemaking

On December 30, 1998, we issued Supplemental Structural Inspection Program AD 98-11-03 R1, amendment 39-10983 (64 FR 989, January 7, 1999) for Boeing Model 727 series airplanes. That AD, in addition to its primary purpose to require inspection of baseline structure, also addresses repairs, alterations, and modifications (RAMs). AD 98-11-03 R1 requires operators to provide damage tolerance-based inspection programs for RAMs that affect structurally significant items or that create new structurally significant items. Certain inspections in this proposed AD are alternative methods of compliance (AMOCs) for the inspections of certain repaired areas that are mandated by AD 98-11-03 R1.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 727-53A0198, Revision 2, dated October 30, 2003.

Revision 2 of the alert service bulletin describes procedures for airplanes based on whether repairs or preventative modifications have been done in accordance with the original issue, Revision 1, or Revision 2 of the service bulletin. These procedures are described in items 1, 2, 3, and 4 below.

1. For airplanes on which no repair or preventative modification has been done in accordance with Boeing Service Bulletin 727-53-0198, dated January 11, 1990; or Revision 1, dated July 25, 1991; or Boeing Alert Service Bulletin 727-53A0198, Revision 2, dated October 30, 2003:

• Revision 2 of the alert service bulletin specifies to do a detailed inspection and high frequency eddy current (HFEC) inspections for cracks of the skin, doubler, and bear strap at the upper and lower hinge cutout.
• If no crack is found during any inspection, Revision 2 of the alert service bulletin specifies to apply certain finishes and repeat the inspections. Doing the preventative modification or repairing in accordance with Revision 2 of the alert service bulletin eliminates only these repetitive inspections.
• If any crack is found during any inspection, and the crack does not exceed certain limits, Revision 2 of the alert service bulletin specifies to repair the crack, and do an HFEC inspection of the trim radius to verify that the crack is removed.
• If any crack is found during any inspection, and the crack exceeds certain limits, Revision 2 of the alert service bulletin specifies to contact Boeing for repair instructions.

2. For airplanes on which any repair or preventative modification has been done in accordance with Boeing Service Bulletin 727-53-0198, dated January 11, 1990:

• Revision 2 of the alert service bulletin specifies to do an inspection to determine if a filler or shim was installed below the S-10 lap joint common to the upper hinge cutout.
• If the filler or shim is missing, Revision 2 of the alert service bulletin specifies to remove the external doubler, do detailed and HFEC inspections of the hinge cutout for cracks, and repair or modify the area if necessary.
• If filler and shim are not missing, Revision 2 of the alert service bulletin specifies to do an HFEC inspection of the pre-existing fastener holes and modifying the pre-existing fastener holes.

3. For airplanes on which any repair or preventative modification has been accomplished in accordance with Boeing Service Bulletin 727-53-0198, dated January 11, 1990; or Revision 1, dated July 25, 1991:

• If pre-existing fastener holes common to the repair or preventative modification were HFEC inspected and oversized: Revision 2 of the alert service bulletin specifies to do an internal HFEC inspection of the bear strap and an external detailed inspection of the repair or preventative modification and its periphery for cracks.
• If pre-existing fastener holes common to the repair or preventative modification were not HFEC inspected: Revision 2 of the alert service bulletin specifies to remove all pre-existing fasteners common to the repair or preventative modification; do an open hole HFEC inspection of the fastener holes for cracks; and oversize the fasteners holes, if no crack is found; and do an internal HFEC inspection of the bear strap and an external detailed inspection of the repair or preventative modification and its periphery for cracks. If any crack is found during the inspection, repair and contact Boeing.

4. For airplanes on which any repair or preventative modification has been done in accordance with Revision 2 of the alert service bulletin, the alert service bulletin specifies to do the following:

• An initial and repetitive HFEC inspections for cracks of the bear strap.
• Initial and repetitive internal inspections for cracks of any repair or preventative modification and its periphery.
• If any crack is found, Revision 2 of the alert service bulletin specifies to repair and contact Boeing.

Revision 2 of the alert service bulletin also describes a preventive modification, which includes doing an open hole HFEC inspection for cracks, oversizing fastener holes, installing doublers, and repairing cracks.

The repairs specified in Revision 2 of the alert service bulletin include doing HFEC inspections for cracks and installing fillers or shims, doublers, and triplers if necessary.

Revision 2 of the alert service bulletin notes that certain inspections have been approved as an AMOC for the inspections of items F-13A and F-14A of the 727 Supplemental Structural Inspection Document mandated by AD 98-11-03 R1 for the areas covered by the repairs/preventative modification.

We have determined that accomplishment of the actions specified in Revision 2 of the alert service bulletin will adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. Therefore, we are proposing this AD, which would require repetitive inspections for cracks of the body skin, doubler, and bear strap at the forward edge of the upper and lower hinge cutouts of the forward entry door, related investigative actions, and corrective action if necessary. This proposed AD also would require a preventive modification. The proposed AD would require you to use the service information described previously to perform these actions, except as discussed under “Differences Between the Proposed AD and the Alert Service Bulletin.”

Differences Between the Proposed AD and the Alert Service Bulletin

Where Revision 2 of Boeing Alert Service Bulletin 727-53A0198 specifies that you may contact the manufacturer for instructions on how to repair certain conditions; and where paragraphs 3.B.9. and 3.B.10. of the Accomplishment Instructions of the alert service bulletin specifies to “repair before further flight and contact the Boeing Company;” this proposed AD would require you to repair those conditions in one of the following ways:

• Using a method that we approve; or
• Using data that meet the certification basis of the airplane, and that have been approved by an Authorized Representative for the Boeing Delegation Option Authorization Organization who has been authorized by the FAA to make those findings.

The alert service bulletin recommends that operators do the preventive modification before the airplane accumulates 60,000 total flight cycles; however, this proposed AD would require the preventative modification before the airplane accumulates 60,000 total flight cycles, or within 3,000 flight cycles after the effective date of the AD, whichever occurs later, unless the repair has already been done. In developing an appropriate compliance time for this proposed AD, we considered the manufacturer's recommendation as well as the amount of time necessary to do the inspections, preventative modification, and any necessary repair. We also considered that some airplanes could be close to 60,000 total flight cycles at the effective date of the AD, and we considered that operators of those airplanes should be allowed a grace period in which to accomplish the preventative modification. In light of all of these factors, we find that a compliance time of 60,000 total flight cycles, or 3,000 flight cycles after the effective date of the AD, whichever occurs later, represents an appropriate interval for affected airplanes to continue to operate without compromising safety.

We also added a grace period of 3,000 flight cycles after the effective date of the AD for the post repair/preventative modification inspections that the service bulletin specifies to be done within 40,000 flight cycles after doing the repair or preventative modification. We find that a compliance time of 40,000 flight cycles after doing the repair or preventative modification, or 3,000 flight cycles after the effective date of the AD, whichever occurs later, represents an appropriate interval for affected airplanes to continue to operate without compromising safety.

Operators should note that where Figures 5 and 6 of the Accomplishment Instructions of the alert service bulletin specify code F, this proposed AD refers to code D. Code F is a typographical error in the service bulletin and does not exist in the table that explains the codes.

Although paragraphs 3.B.9. and 3.B.10. of the Accomplishment Instructions of the alert service bulletin specify that operators should contact Boeing after repairing cracks, this proposed AD does not include that requirement.

Operators should note that, although the Appendix A of the alert service bulletin contains instructions for reporting discrepancies to Boeing Customer Support Technical Services, this proposed AD does not require those actions.

These differences have been coordinated with Boeing.

Clarification of Alert Service Bulletin

For airplanes on which the repair or preventative modification has not been done, paragraph 1.E., Compliance, of the alert service bulletin does not specify the applicable paragraphs in the Accomplishment Instructions of the alert service bulletin for doing the actions. Paragraphs 3.B.1 through 3.B.7 of the Accomplishment Instructions of the alert service bulletin describe the actions for airplanes on which the repair or preventative modification has not been done.

Costs of Compliance

There are about 1,015 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.

Authority for This Rulemaking

The FAA's authority to issue rules regarding aviation safety is found in Title 49 of the United States Code. Subtitle I, Section 106 describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the agency's authority.

This rulemaking is promulgated under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify that the proposed regulation:

1. Is not a “significant regulatory action” under Executive Order 12866;

2. Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and

3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.