Skip to Content

Proposed Rule

Airworthiness Directives; Boeing Model 757-200, -200CB, and -200PF Series Airplanes

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Boeing Model 757 series airplanes, that currently requires repetitive inspections for excessive wear of the internal and external splines of the torque tube couplings of the trailing edge flaps, and replacement of the couplings, if necessary. That AD also provides an optional modification that, if installed, constitutes terminating action for the inspection requirements. This action would expand the applicability of the existing AD and require new inspections of the torque tube assemblies and certain gearbox assemblies and universal joints in the drive system for the inboard trailing edge flaps, and follow-on actions, if necessary. For certain airplanes, this action also would require the previously optional modification and/or a new modification, which would terminate certain inspections. The actions specified by the proposed AD are intended to prevent separations in the drive system for the inboard trailing edge flaps, which could cause a flap skew condition that could result in damage to the flaps or fuselage, and consequent reduced controllability of the airplane.

DATES:

Comments must be received by July 15, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-329-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Start Printed Page 37358Comments may be inspected at this location between 9:00 a.m. and 3:00 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. 2001-NM-329-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.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Technical Information: Douglas Tsuji, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-1506; fax (425) 227-1181.

Other Information: Judy Golder, Airworthiness Directive Technical Editor/Writer; telephone (425) 227-1119, fax (425) 227-1232. Questions or comments may also be sent via the Internet using the following address: judy.golder@faa.gov. Questions or comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

  • Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
  • For each issue, state what specific change to the proposed AD is being requested.
  • Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

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 2001-NM-329-AD.” The postcard will be date-stamped and returned to the commenter.

Availability of NPRMs

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. 2001-NM-329-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On November 9, 1992, the FAA issued AD 92-25-01, amendment 39-8416 (57 FR 54298, November 18, 1992), applicable to certain Boeing Model 757 series airplanes, to require visual inspections of the internal and external splines of the trailing edge flap drive torque tube coupling assembly for excessive wear, and replacement of the coupling, if necessary. That AD also provides an optional modification that, if installed, constitutes terminating action for the inspection requirements. That action was prompted by reports of excessive wear on the aft end of the trailing edge flap drive torque tube coupling. The requirements of that AD are intended to prevent damage caused by skewed flaps resulting from excessive wear of the splines of the trailing edge flap drive torque tube coupling.

Actions Since Issuance of Previous Rule

Since the issuance of that AD, the FAA has received several reports of separations in the drive system for the inboard trailing edge flaps on Boeing Model 757-200, -200CB, and -200PF series airplanes. These separations caused a flap skew condition, in which one end of a flap did not move to the commanded position. These separations have been attributed to various discrepancies in the drive system for the trailing edge flaps, including:

  • Worn splines in the torque tube assemblies;
  • Corroded and worn bearings from loss of lubricant, which permitted axial shaft movement and subsequent bevel gear separation inside angle gearbox assemblies; and
  • Worn universal joints (U-joints) caused by the loss of boots and subsequent wear on the drive shaft assembly between the inboard transmission of the inboard flaps and the angle tee gearbox assembly.

These discrepancies could cause a flap skew condition, which could result in damage to the flaps or fuselage and consequent reduced controllability of the airplane.

The existing AD applies to Model 757 series airplanes with line numbers 1 through 411 inclusive and 413 through 432 inclusive. Since the issuance of that AD, the FAA has determined that certain other Model 757 series airplanes (i.e., Model 757-200, -200CB, and -200PF series airplanes) may also be subject to the discrepancies described previously. Therefore, these additional airplanes also may be subject to the identified unsafe condition.

Also, as stated previously, AD 92-25-01 provides for an optional modification per Boeing Service Bulletin 757-27-0099, dated March 12, 1992, for airplanes that were delivered without coupling seals on torque tube assemblies 3 and 6. That modification includes replacement of torque tube assemblies 3 and 6 with improved torque tube assemblies and installation of a sealant plug in the shafts of four gearboxes. The FAA has now determined that long-term continued operational safety will be better assured by requiring installation of this modification (to remove the source of the problem), rather than by requiring repetitive inspections. In some instances, long-term inspections may not provide the degree of safety assurance necessary for the transport airplane fleet. This, coupled with a better understanding of the human factors associated with numerous continual inspections, has led the FAA to consider placing less emphasis on inspections and more emphasis on design improvements. Therefore, this proposed AD would require doing the previously optional modification. Doing this modification eliminates the need for the repetitive inspections for excessive wear of torque tube assemblies 3 and 6.Start Printed Page 37359

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin 757-27A0125, Revision 1, including Appendices A and B, dated December 2, 1999. That service bulletin describes procedures for inspecting certain torque tube assemblies, certain gearbox assemblies, and U-joints on the drive shaft assembly in the drive system for the inboard trailing edge flaps. The inspection of the torque tube assemblies involves performing a general visual inspection for excessive wear of external splines and, if excessive wear is found, measuring the distance over pins, measuring the outer diameter, if necessary, and repeating the inspection or replacing the torque tube assembly, as necessary. The inspection of the gearbox assemblies involves measuring axial movement, and replacing the gearbox assembly with a new assembly, if necessary. The inspection of the U-joints on the drive shaft assembly involves measuring the maximum and minimum distance between the upper and lower yoke, and replacing the drive shaft assembly with a new assembly, if necessary. Doing the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

The FAA also has reviewed and approved Boeing Service Bulletin 757-27-0107, dated June 16, 1994. Among other actions, for airplanes delivered without coupling seals on torque tube assemblies 4 and 5, that service bulletin describes procedures for a modification that involves replacing torque tube assemblies 4 and 5 with new, improved torque tube assemblies, and changing related angle and tee gearbox assemblies of the drive system. The changes to the angle gearbox assembly involve replacing certain coupling halves with improved coupling halves, installing sealant, and changing the part number of the assembly. The changes to the tee gearbox assembly involve cleaning certain holes, installing sealant, and changing the part number of the assembly. Doing this modification eliminates the need for the repetitive inspections for excessive wear of torque tube assemblies 4 and 5.

Explanation of Change to Existing Requirements

In the “Restatement of Requirements of AD 92-25-01” in this proposed AD, the FAA has revised paragraph (a) of the existing AD to clarify that the visual inspection applies to the torque tube 3 and 6 coupling splines. Also, the FAA has clarified the existing requirement to specify that the required inspection is a “general visual inspection.” A note has been added under the new requirements of this proposed AD to define that inspection.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would supersede AD 92-25-01 to continue to require repetitive inspections of the internal and external splines of the trailing edge flap drive torque tube coupling assemblies for excessive wear, and replacement of the couplings, if necessary. The proposed AD also would require accomplishment of the actions specified in Boeing Alert Service Bulletin 757-27A0125, Revision 1. For certain airplanes, the proposed AD also would require accomplishment of Boeing Service Bulletin 757-27-0099, and/or certain actions in Boeing Service Bulletin 757-27-0107, as described previously.

Cost Impact

There are approximately 979 airplanes of the affected design in the worldwide fleet.

In AD 92-25-01, the FAA estimated that approximately 279 U.S.-registered airplanes would be subject to the inspections in that AD. For these airplanes, the currently required inspections take approximately 2 work hours per airplane, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $33,480, or $120 per airplane, per inspection cycle.

The FAA estimates that approximately 283 U.S.-registered airplanes (Group 1 of Boeing Alert Service Bulletin 757-27A0125, Revision 1) would be subject to the proposed inspection of torque tube assemblies 3 and 6. This inspection would take approximately 2 work hours per airplane, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of these new proposed inspections on U.S. operators of Group 1 airplanes is estimated to be $33,960, or $120 per airplane, per inspection cycle.

The FAA estimates that approximately 376 U.S.-registered airplanes (Groups 1 and 2 of Boeing Alert Service Bulletin 757-27A0125, Revision 1) would be subject to the proposed inspection of torque tube assemblies 4 and 5. This inspection would take approximately 2 work hours per airplane, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of these new proposed inspections on U.S. operators of Group 2 airplanes is estimated to be $45,120, or $120 per airplane, per inspection cycle.

The FAA estimates that 643 U.S.-registered airplanes (Groups 1, 2, and 3 of Boeing Alert Service Bulletin 757-27A0125, Revision 1) would be subject to the new proposed inspections of the gear box assemblies and U-joints of the drive shaft assembly. These inspections would take approximately 4 work hours per airplane, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of these new proposed inspections on U.S. operators is estimated to be $154,320, or $240 per airplane, per inspection cycle.

The FAA estimates that approximately 283 U.S.-registered airplanes (Group 1 of Boeing Alert Service Bulletin 757-27A0125, Revision 1) would be subject to the proposed modification that involves replacement of torque tube assemblies 3 and 6. This modification would take approximately 5 work hours per airplane, at an average labor rate of $60 per work hour. Required parts would cost approximately $4,550. Based on these figures, the cost impact of this proposed modification on U.S. operators is estimated to be $1,372,550, or $4,850 per airplane.

The FAA estimates that approximately 376 U.S.-registered airplanes (Groups 1 and 2 of Boeing Alert Service Bulletin 757-27A0125, Revision 1) would be subject to the proposed modification that involves replacement of torque tube assemblies 4 and 5. This modification would take approximately 5 work hours per airplane, at an average labor rate of $60 per work hour. Required parts will cost approximately $4,550. Based on these figures, the cost impact of this proposed modification on U.S. operators is estimated to be $1,823,600, or $4,850 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. Start Printed Page 37360

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this 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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

Start Part

PART 39—AIRWORTHINESS DIRECTIVES

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

Start Authority

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

End Authority
[Amended]

2. Section 39.13 is amended by removing amendment 39-8416 (57 FR 54298, November 18, 1992), and by adding a new airworthiness directive (AD), to read as follows:

Boeing: Docket 2001-NM-329-AD. Supersedes AD 92-25-01, Amendment 39-8416.

Applicability: Model 757-200, -200CB, and -200PF series airplanes; line numbers (L/Ns) 1 through 979 inclusive; certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (h) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent separations in the drive system for the inboard trailing edge flaps, which could cause a flap skew condition that could result in damage to the flaps or fuselage, and consequent reduced controllability of the airplane, accomplish the following:

Restatement of Requirements of AD 92-25-01:

Repetitive Visual Inspections and Corrective Actions

(a) For airplanes with L/Ns 1 through 411 inclusive and 413 through 432 inclusive: Prior to the accumulation of 2,000 total flight cycles, or within the next 200 flight cycles after April 30, 1990 (the effective date of AD 90-08-16, amendment 39-6574), whichever occurs later, and thereafter at intervals not to exceed 2,000 flight cycles, perform a general visual inspection of the torque tube 3 and 6 coupling splines, in accordance with Boeing Service Letter 757-SL-27-52-B, dated April 30, 1990.

Note 2:

Operators who have conducted inspections of the torque tube coupling splines prior to December 23, 1992 (the effective date of AD 92-25-01, amendment 39-8416), in accordance with Boeing Service Letter 757-SL-27-52, dated January 31, 1990, or Boeing Service Letter 757-SL-27-52-A, dated March 21, 1990, are considered to be in compliance with paragraph (a) of this AD.

(1) If the measurement over the pin, as detailed in the service letter, is less than 1.8605 inches but equal to or greater than 1.8533 inches, repeat the inspection within 1,000 flight cycles, until the requirements of paragraph (c) or (f) of this AD have been accomplished.

(2) If the measurement over the pin, as detailed in the service letter, is less than 1.8533 inches, replace the coupling before further flight, in accordance with the service letter.

New Requirements of This AD:

Note 3:

For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

New Repetitive Inspections: Torque Tubes 3 and 6

Note 4:

If the requirements of paragraph (f) of this AD have been accomplished before the effective date of this AD, inspection per paragraph (b) of this AD is not required.

(b) For airplanes with L/Ns 1 through 411 inclusive and 413 through 432 inclusive, which are identified as Group 1 airplanes in Boeing Alert Service Bulletin 757-27A0125, Revision 1, including Appendices A and B, dated December 2, 1999: Do a general visual inspection for excessive wear of torque tube assemblies 3 and 6, per the service bulletin. Do the initial inspection at the time specified in paragraph (b)(1) or (b)(2) of this AD, as applicable. If no wear is found, repeat the inspection every 3,000 flight cycles or 24 months, whichever comes first, until paragraph (f) of this AD has been accomplished. Doing paragraph (b) of this AD terminates the requirements of paragraph (a) of this AD for torque tube assemblies 3 and 6.

(1) For airplanes on which the inspection in paragraph (a) of this AD has been done prior to the effective date of this AD: Inspect within 3,000 flight cycles after the most recent inspection done PRIOR to the effective date of this AD per paragraph (a) of this AD, or within 24 months after the effective date of this AD, whichever is first.

(2) For airplanes on which the inspection in paragraph (a) of this AD has NOT been done prior to the effective date of this AD: Inspect prior to the accumulation of 3,000 total flight cycles, within 24 months since the airplane's date of manufacture, or within 18 months after the effective date of this AD, whichever is latest.

Note 5:

Inspections, measurements, and replacements done prior to the effective date of this AD per Boeing Alert Service Bulletin 757-27A0125, dated July 17, 1997, are considered acceptable for compliance with the corresponding requirements of paragraphs (b), (c), (d), and (e) of this AD.

New Repetitive Inspections: Torque Tubes 4 and 5

Note 6:

If the requirements of paragraph (g) of this AD have been accomplished before the effective date of this AD, inspection per paragraph (c) of this AD is not required.

(c) For airplanes with L/Ns 1 through 411 inclusive and 413 through 580 inclusive, which are identified as Groups 1 and 2 airplanes in Boeing Alert Service Bulletin 757-27A0125, Revision 1, including Appendices A and B, dated December 2, 1999: Prior to the accumulation of 3,000 total flight cycles, within 24 months since the airplane's date of manufacture, or within 18 months after the effective date of this AD, whichever is latest, do a general visual inspection for excessive wear of torque tube assemblies 4 and 5, per the service bulletin. If no wear is found, repeat the inspection every 3,000 flight cycles or 24 months, whichever comes first, until paragraph (g) of this AD has been accomplished. Start Printed Page 37361

Corrective Actions: Torque Tubes 3, 4, 5, and 6

(d) If any wear is found during any inspection required by paragraph (b) or (c) of this AD: Before further flight, measure the distance of the measurement over pins, per Boeing Alert Service Bulletin 757-27A0125, Revision 1, including Appendices A and B, dated December 2, 1999.

(1) If the distance is 1.8337 inches or more, repeat the general visual inspection required by paragraph (b) or (c) of this AD at the applicable interval specified in Table 1 of Figure 7 of the service bulletin, until the actions in paragraphs (f) (for torque tube assemblies 3 and 6) and (g) (for torque tube assembles 4 and 5) have been done.

(2) If the distance is less than 1.8337 inches, do the actions in paragraphs (d)(2)(i) and (d)(2)(ii) of this AD, per the service bulletin.

(i) Before further flight, measure the distance of the outside diameter, as shown in Table 1 of Figure 7 of the service bulletin.

(ii) Replace the affected torque tube assembly with a new torque tube assembly at the applicable time specified in Table 1 of Figure 7 of the service bulletin.

New Repetitive Inspections: Gearbox Assemblies and Universal Joints

(e) For airplanes with L/Ns 1 through 979 inclusive: Prior to the accumulation of 3,000 total flight cycles, within 24 months since the airplane's date of manufacture, or within 18 months after the effective date of this AD, whichever is latest, perform an inspection to measure the axial movement of the angle and tee gearbox assemblies and the distance between the upper and lower yokes of the universal joints (U-joints) of the drive shaft assemblies, per Boeing Alert Service Bulletin 757-27A0125, Revision 1, including Appendices A and B, dated December 2, 1999. Repeat these measurements every 3,000 flight cycles or 24 months, whichever comes first, and do paragraphs (e)(1) and (e)(2) of this AD, as applicable.

(1) If any measurement of the axial movement of the gearbox assembly is more than 0.015 inch, as specified in the service bulletin: Before further flight, replace the gearbox assembly with a new gearbox assembly, per the service bulletin.

(2) If the distance between the upper and lower yokes of the U-joints is more than 0.020 inch, as specified in Steps 3 and 6 of Figure 6 of the service bulletin: Before further flight, replace the drive shaft assembly with a new drive shaft assembly, per the service bulletin.

Terminating Action

(f) For airplanes with L/Ns 1 through 411 inclusive and 413 through 432 inclusive: Within 3 years after the effective date of this AD, modify the airplane by replacing torque tube assemblies number 3 and 6 with new, improved torque tube assemblies, and installing a sealant plug in the shafts of four gearboxes, according to Boeing Service Bulletin 757-27-0099, dated March 12, 1992. Doing this paragraph terminates the inspections required by paragraphs (a) and (b) of this AD.

(g) For airplanes with L/Ns 1 through 580 inclusive: Within 3 years after the effective date of this AD, modify the airplane by replacing torque tube assemblies number 4 and 5 with new, improved torque tube assemblies, and changing the related angle and tee gearbox assemblies, per Boeing Service Bulletin 757-27-0107, dated June 16, 1994. The changes for the related tee and angle gearbox assemblies are shown in Figures 6 and 7, respectively, of the service bulletin. Doing this paragraph terminates the inspections required by paragraph (c) of this AD.

Note 7:

No terminating action has been identified for the inspections specified in paragraph (e) of this AD.

Alternative Methods of Compliance

(h) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

Note 8:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permits

(i) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Start Signature

Issued in Renton, Washington, on May 15, 2002.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 02-12949 Filed 5-28-02; 8:45 am]

BILLING CODE 4910-13-P