AD 96-06-09

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AD Number:
96-06-09
Document Type:
AD Final Rules
Docket Number:
96-NM-50-AD
Subject Heading:
Airworthiness Directives; Boeing Model 767 Series Airplanes
Subject:
Trailing Edge Flap Inspection
Status:
Current
Citation:
(Federal Register: March 21, 1996 (Volume 61, Number 56))
Citation Publish Date:
03/21/1996
Effective Date:
04/05/1996
Make:
The Boeing Company
Model:
767-200 Series | 767-300 Series | 767-300F Series
Product Type:
Aircraft
Product Subtype:
Large Airplane
Affected AD:
Superseded AD:
Affected By:
Superseded By:
Service/Office:
Office of Primary Responsibility:
CFR Part Reference:
Part 39 (61 FR 11541 NO. 56 03/21/96)
Comments:
AIRWORTHINESS DIRECTIVES FINAL RULES: 96-06-09
CITATION:   [Federal Register: March 21, 1996 (Volume 61, Number 56)]

PAGE NUMBER:   [Page 11541]

DOCKET NUMBER:   96-NM-50-AD

AMENDMENT:   39-9546

AD NUMBER:   96-06-09

SUBJECT HEADING:   Airworthiness Directives; Boeing Model 767 Series Airplanes

ACTION:   Final rule; request for comments

SUMMARY:  
This amendment adopts a new airworthiness directive (AD) that is applicable to three Boeing Model 767 series airplanes, serial numbers 26847, 27048, and 27049. This action requires a functional check of the trailing edge flap drive bypass valve, and eventual replacement of the control valve module for the trailing edge flaps with an improved module. This amendment is prompted by reports of failure of the bypass valve motor in the control valve module of the trailing edge flaps due to hydraulic fluid contamination. The actions specified in this AD are intended to prevent such failure, which could result in loss of shutdown protection for the trailing edge flap drive; this condition could result in reduced controllability of the airplane in the event of uncommanded or asymmetrical flap motion.

DATES:   Effective April 5, 1996. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of April 5, 1996. Comments for inclusion in the Rules Docket must be received on or before May 20, 1996.

ADDRESSES:  
Submit comments in triplicate to the Federal Aviation Administration (FAA),
Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 96-NM-50-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

The service information referenced in this AD 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; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT:  
Susan Letcher, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington; telephone (206) 227-2670; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION:  
On September 27, 1993, the FAA issued AD 93-19-05, amendment 39-8703 (58 FR 54940, October 25, 1993), which is applicable to Boeing Model 767 series airplanes, line positions 001 through 402 inclusive. That AD requires (initially) various functional checks of: 1. the leading edge slat shutoff valve, 2. the trailing edge flap drive bypass valve, 3. the leading edge slat long term shutoff control, and 4. the leading edge slat drive mechanical rigging.

In addition, that AD requires installation of terminating modifications for the required functional checks. One of these modifications involves replacing the bypass valve motor of the control valve module for the trailing edge flaps.

AD 93-19-05 was prompted by a report of an uncommanded slat extension during cruise, and several instances of an inoperative trailing edge flap bypass valve motor. These instances were attributed to hydraulic fluid in the bypass valve motor. The requirements of that AD are intended to prevent uncommanded deployment of leading edge slats, which could result in structural damage to the wing and consequent degradation of flight control. Additionally, the requirements of that AD are intended to ensure shutdown protection for the trailing edge flap drive in the event of uncommanded or asymmetrical flap motion.

Since the issuance of AD 93-19-05, the manufacturer has advised the FAA that three airplanes (those having serial numbers 26847, 27048, and 27049) were delivered on which the replacement of the bypass valve motor in the control valve module for the trailing edge flaps had not been accomplished during production. Those three airplanes were not included in the applicability of AD 93-19-05; however, they are subject to the same unsafe condition addressed by that AD. The FAA has determined that loss of shutdown protection for the trailing edge flap drive due to hydraulic fluid contamination of the bypass valve motor could occur on these three airplanes.

The FAA has reviewed and approved Boeing Service Bulletin 767-27A0094, Revision 5, dated June 9, 1994, which describes (among other actions) procedures to perform a one-time functional check of the bypass valve of the trailing edge flap drive.

The FAA has also reviewed and approved Boeing Service Bulletin 767-27-0138, dated August 17, 1995, which describes procedures for replacement of the control valve module for the trailing edge flaps with an improved module on the three airplanes having serial numbers 26847, 27048, and 27049. The bypass valve motor in the improved module was redesigned to ensure that the motor is hermetically sealed. Accomplishment of this replacement will prevent hydraulic fluid contamination.

Since an unsafe condition has been identified that is likely to exist or develop on other Boeing Model 767 series airplanes of the same type design, this AD is being issued to prevent loss of shutdown protection for the trailing edge flap drive, which could result in reduced controllability of the airplane in the event of uncommanded or asymmetrical flap motion. This AD requires a one-time functional check of the trailing edge flap drive bypass valve, and eventual replacement of the control valve module for the trailing edge flaps with an improved module. The actions are required to be accomplished in accordance with the service bulletins described previously. This AD applies only to airplanes having serial numbers 26847, 27048, and 27049.

[NOTE: The FAA's normal policy is that when an AD requires a substantive change, such as a change (expansion) in its applicability, the "old" AD is superseded by removing it from the system and a new AD is added. In the case of this AD action, the FAA normally would have proposed superseding AD 93-19-05 to expand its applicability to include the three additional affected airplanes. However, in reconsideration of the entire fleet size that would be affected by a supersedure action, and the consequent workload associated with revising maintenance record entries, the FAA has determined that a less burdensome approach is to issue a separate AD applicable only to the three additional airplanes. This AD does not supersede AD 93-19-05; airplanes listed in the applicability of AD 93-19-05 are required to continue to comply with the requirements of that AD. This AD is a separate AD action, and is applicable only to airplanes having serial numbers 26847, 27048, and 27049.]

Operators should note that the manufacturer's recommended compliance time for accomplishment of the functional check is within 400 flight hours after receipt of the service bulletin. While the FAA agrees that 400 flight hours would normally be an appropriate compliance time, this AD specifies a compliance time of 25 days after the effective date of this AD. This compliance time was developed by taking into account the date that the initial service bulletin recommended (September 28, 1989) for accomplishment of the actions and the time that has elapsed since that date. The FAA considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition, as well as the time necessary to perform the functional check (1 work hour). In light of these factors, the FAA finds 25 days to be an appropriate compliance time for initiating the required functional check.

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 96-NM-50-AD." The postcard will be date stamped and returned to the commenter.

The regulations adopted herein will not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES." List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment

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

PART 39 - AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows: Authority: 49 USC 106(g), 40113, 44701. § 39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive:

REGULATORY TEXT:  
96-06-09 BOEING: Amendment 39-9546. Docket 96-NM-50-AD.

Applicability: Model 767 series airplanes, having serial number 26847, 27048, or 27049, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 (d) 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 loss of shutdown protection for the trailing edge flap drive, which could result in reduced controllability of the airplane in the event of uncommanded or asymmetrical flap motion, accomplish the following:

(a) Within 25 days after the effective date of this AD, perform a one-time functional check to ensure that the bypass valve motor in the control valve module for the trailing edge flaps is operational, in accordance with Part II of the Accomplishment Instructions of Boeing Service Bulletin 767-27A0094, Revision 5, dated June 9, 1994. If a failed bypass valve motor is found, prior to further flight, accomplish the replacement required by paragraph (b) of this AD.

(b) Within 60 days after the effective date of this AD, replace the control valve module for the trailing edge flaps with an improved module having a redesigned bypass valve motor that is hermetically sealed, in accordance with Boeing Service Bulletin 767-27-0138, dated August 17, 1995.

(c) As of the effective date of this AD, no person shall install either a control valve module, part number S256T005-7, or a bypass valve, part number S256T005-4, on any airplane.

(d) 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, Transport Airplane Directorate. 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

(e) 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.

(f) The functional check shall be done in accordance with Boeing Service Bulletin 767- 27A0094, Revision 5, dated June 9, 1994. The replacement shall be done in accordance with Boeing Service Bulletin 767-27-0138, dated August 17, 1995. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(g) This amendment becomes effective on April 5, 1996.

FOOTER: