AD 97-16-01

Effective August 12, 1997.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of August 12, 1997.

Comments for inclusion in the Rules Docket must be received on or before September 26, 1997.

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 97-NM-137-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

The service information referenced in this AD may be obtained from AI(R) American Support, Inc., 13850 Mclearen Road, Herndon, Virginia 20171. 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.

Bud Schroeder, Aerospace Engineer, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2148; fax (425) 227-1149.

The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom, recently notified the FAA that an unsafe condition may exist on certain British Aerospace (Jetstream) Model 4101 airplanes. The CAA advises that, during full-scale fatigue tests on a Jetstream Model 4101 test article, cracking was found in the roller guide shear cleats of the passenger door. Such cracking also was found during in-service maintenance inspections. This cracking is attributed to fatigue-related stress. Fatigue-related cracking in the roller guide shear cleats of the passenger door, if not detected and corrected in a timely manner, could result in structural failure of the passenger door, and consequent rapid depressurization of the airplane or loss of the passenger door while the airplane is in flight.

British Aerospace has issued Jetstream Alert Service Bulletin J41-A52-043, Revision 2, dated May 6, 1997, which describes procedures for repetitive detailed visual inspections to detect cracks of the roller guide shear cleats of the passenger door. The service bulletin also describes procedures for replacement of any cracked shear cleat with a new shear cleat. The CAA classified the alert service bulletin as mandatory and issued British airworthiness directive 003-03-97 in order to assure the continued airworthiness of these airplanes in the United Kingdom.

British Aerospace also has issued Jetstream Service Bulletin J41-52-050, dated May 6, 1997. The service bulletin describes procedures for modification of the passenger door, which will eliminate the need for repetitive detailed visual inspections. The modification involves installation of a one-piece machined abutment fitting to replace the existing roller guide intercostal and loose shear cleats of the passenger door. The modification will strengthen the structural support of the roller guides of the passenger door, which will minimize the possibility of fatigue cracking in the roller guide support structure.

This airplane model is manufactured in the United Kingdom and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the CAA has kept the FAA informed of the situation described above. The FAA has examined the findings of the CAA, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, this AD is being issued to detect and correct fatigue-related cracking in the shear cleats of the roller guide structural support of the passenger door, which could result in structural failure of the passenger door, and consequent rapid depressurization of the airplane or loss of the passenger door while the airplane is in flight. This AD requires repetitive detailed visual inspections to detect cracks of the roller guide shear cleats of the passenger door, and replacement of any cracked shear cleat with a new shear cleat. This AD also provides for an optional terminating modification that constitutes terminating action for the repetitive inspection requirements. The actions are required to be accomplished in accordance with the service bulletins described previously.

Operators should note that, while it is not the FAA's normal policy to allow flight with known cracks, this AD does permit further flight when one roller guide shear cleat of the passenger door is cracked within certain limits. The results of a review, conducted by the manufacturer, shows that the subject passenger door continues to comply with the applicable certification basis when cracking in all eight of roller guide shear cleats does not exceed certain limits. Therefore, according to the review, if certain crack size limits are strictly observed, and corrective action is taken to replace all cracked shear cleats within a certain number of landings, the cracks will not grow to a size that would create an unacceptable risk of structural failure. The CAA concurs with the findings of this review. In consideration of these findings and based on the FAA's criteria for flight with known cracking, the FAA has determined that further flight when one roller guide shear cleat of the passenger door is cracked within certain limits is permissible for an interim period. However, the FAA has determined that further flight with widespread (i.e., more than one crack) known cracking is not permitted. Therefore, for cases where more than one cracked shear cleat is detected within certain limits, this AD requires replacement of all cracked shear cleats prior to further flight.

The FAA is considering further rulemaking action to supersede this AD to require the accomplishment of the optional terminating modification currently specified in this AD. However, the planned compliance time for accomplishment of that action is sufficiently long so that prior notice and time for public comment will be practicable.

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.

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 97-NM-137-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.

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

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:

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

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