Airworthiness Directives; Dornier Model 328-100 Series Airplanes

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 all Dornier Model 328-100 series airplanes, that currently requires certain revisions to the airplane flight manual, replacement of certain de-icing boots in the air intake duct assemblies of the engine with re-designed units, repetitive inspections of the boots to find discrepancies, and corrective action if necessary. This action would also require modification of the engine air inlet de-icing system. This action would extend the repetitive inspection interval required by the existing AD, and would add repetitive debonding/delamination and leakage inspections of the de-icing boots, and corrective action if necessary. Initiation of the extended repetitive inspections and new repetitive inspections would end the repetitive inspections required by the existing AD. The actions specified by the proposed AD are intended to prevent engine malfunction due to failure of the engine air inlet de-icing system, which could result in reduced controllability of the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by May 3, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-294-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 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. 2002-NM-294-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 or 2000 or ASCII text.

The service information referenced in the proposed rule may be obtained from AvCraft Aerospace GmbH, P.O. Box 1103, D-82230 Wessling, Germany. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Tom Groves, Aerospace Engineer, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-1503; fax (425) 227-1149.

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 2002-NM-294-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. 2002-NM-294-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On March 14, 1995, the FAA issued AD 95-04-51, amendment 39-9179 (60 FR 15037, March 22, 1995), applicable to all Dornier Model 328-100 series airplanes, to require certain revisions to the airplane flight manual (AFM), replacement of certain de-icing boots in the air intake duct assemblies of the engine with re-designed units, and inspections of the boots to find discrepancies. That action was prompted by reports of failures of the engine air inlet de-icing system, including debonding of the boots from the engine air intake ducts, failure of the air-tight chambers in the boots, and malfunction and subsequent shutdown of an engine during flight. The requirements of that AD are intended to prevent engine malfunction due to failure of the engine air inlet de-icing system.

Actions Since Issuance of Previous Rule

In the preamble to AD 95-04-51, we specified that the actions required by that AD were considered to be “interim action” and that we may consider further rulemaking action. The manufacturer now has developed an improved modification of the engine air inlet de-icing system. We have determined that further rulemaking is necessary to require the modification on affected airplanes; this proposed AD follows from that determination.

Explanation of New Service Information

The manufacturer has issued the following Dornier Service Bulletins:

• SB-328-71-122, Revision 1, dated May 10, 1999, which describes procedures for the modification of the engine air intake ducts. The service bulletin references Westland Aerospace Limited Service Bulletin SB-WAL328-71-122, dated September 25, 1995, as an additional source of service information for accomplishment of the modification.
• SB-328-71-125, Revision 3, dated May 10, 1999, which describes procedures for modification of the engine air inlet de-icing system, which includes installation of new, improved engine air intake ducts, installation of geometrically adapted de-icing boots, and installation of an improved outlet cover plate of the bypass duct. The service bulletin also describes procedures for doing detailed visual and tactile inspections of certain de-icing boots for discrepancies (flat spots, softness, or other irregularities in concave sections, or improper sealing), and corrective action if discrepancies are found. The corrective action includes doing a debonding inspection, as specified in the airplane maintenance manual, and if the debonded area is outside the allowable limits, replacing all three de-icing boots before further flight.

Dornier Service Bulletin SB-328-71-125, Revision 3, also references Westland Aerospace Limited Service Bulletin SB-WAL328-71-125, Revision 1, dated September 25, 1995, as an additional source of service information for installation of the cover plate of the bypass duct outlet.

• SB-328-30-432, dated April 26, 2002, which describes procedures for doing detailed visual and tactile inspections of the engine air inlet de-icing boots to find discrepancies (flat or soft spots in concave sections, defects on the de-icing boots, or improper sealing), and corrective action if discrepancies are found. The corrective action includes doing a debonding/delamination and leakage inspection, and replacing any delaminated de-icing boot outside the allowable bonding limits. The inspections are to be repeated thereafter at certain intervals.

The Luftfahrt-Bundesamt (LBA), which is the airworthiness authority for Germany, classified the Dornier service information as mandatory and issued German airworthiness directives 1995-156/3, dated July 1, 1999; and 2002-256, dated September 5, 2002, to ensure the continued airworthiness of these airplanes in Germany.

FAA's Conclusions

This airplane model is manufactured in Germany 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 LBA has kept us informed of the situation described above. We have examined the findings of the LBA, 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.

Explanation of Requirements of Proposed Rule

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, the proposed AD would supersede AD 95-04-51 to continue to require the revisions to the AFM, replacement of certain de-icing boots in the air intake duct assemblies of the engine with re-designed units, and repetitive inspections of the boots to find discrepancies, and corrective action if necessary. This action also would require modification of the engine air inlet de-icing system and would add a new AFM revision which changes the compliance time for the functional test required by the existing AD. It would also extend the repetitive inspection interval required by the existing AD, and would add repetitive debonding/delamination and leakage inspections of the de-icing boots, and corrective action if necessary. Initiation of the extended repetitive inspections and debonding/delamination and leakage inspections would end the repetitive inspections required by the existing AD. The actions would be required to be accomplished in accordance with the Dornier service bulletins described previously, except as discussed below.

Differences Among German Airworthiness Directives, Dornier Service Bulletins, and Proposed AD

The German airworthiness directives do not contain a requirement for continued accomplishment of the functional test required by the existing AD, but this proposed AD does continue to require accomplishment of the functional test.

German airworthiness directive 2002-256 and Service Bulletin SB-328-30-432 specify a repetitive interval of 800 flight hours for the detailed inspection and a debonding/delamination and leakage inspection of the engine air intake de-icing system specified in paragraph 2.B.2. of the service bulletin. We have determined that, since paragraph 2.B.1.(1) of the service bulletin specifies the same detailed inspection at a 60-flight-hour interval, it is not necessary to also require the detailed inspection at the 800-flight-hour interval.

In addition, this proposed AD would require accomplishment of the debonding/delamination and leakage inspection described in paragraph 2.B.2.(2) of the service bulletin at intervals not to exceed 400 flight hours, in lieu of every 800 flight hours. We have reviewed the service history of the U.S.-registered fleet of Model 328-100 series airplanes and have found that an 800-flight-hour debonding/delamination and leakage inspection interval would not be sufficient to find progressive inlet boot delamination/debonding before it reaches a point where it represents a hazard to the airplane. In developing an appropriate compliance time for this action, we considered not only the safety implications and the LBA recommendations, but the manufacturer's recommendation and the degree of urgency associated with addressing the subject unsafe condition. In light of all of these factors, we find an initial compliance time of “within 400 flight hours after the effective date of this AD,” and repetitive intervals not to exceed 400 flight hours after the initial inspection, for doing the proposed debonding/delamination and leakage inspections to be warranted, in that those times represent appropriate intervals of time allowable for affected airplanes to continue to operate without compromising safety.

Although Service Bulletin SB-328-30-432 defines the inspection as “visual” and “touch,” and SB-328-71-125 defines the inspection as “detailed visual” and “tactile,” this proposed AD defines that inspection as a “detailed” inspection. In addition, we have changed all references to a “detailed visual inspection” in the existing AD to “detailed inspection” in this proposed AD. A new note has been added to the proposed AD to define this inspection.

German airworthiness directive 1995-156/3 and Service Bulletin SB-328-71-125 recommend modification of the air intake/de-icing system “not later than December 31, 1995,” and “weekly” visual and tactile inspections. This proposed AD would require the modification within 60 flight hours after the effective date of this AD. When German airworthiness directive 1995-156/2 was issued on November 2, 1995, we did not take parallel action because we had previously issued an alternative method of compliance for the existing AD which approved the modification of the air intake/de-icing system. We are now requiring the modification on all airplanes that have not yet been modified.

In addition, although “weekly” visual and tactile inspections are specified in the German airworthiness directive and Service Bulletin SB-328-71-125, this proposed AD would require only a one-time inspection after accomplishment of the modification, then repetitive detailed inspections at intervals not to exceed 60 flight hours and debonding/delamination and leakage inspections at intervals not to exceed 400 flight hours, per the procedures specified in Service Bulletin SB-328-30-432.

Service Bulletin SB-328-30-432 describes procedures for completing a reporting sheet with inspection results, but this proposed AD does not include such a requirement.

Work Hour Rate Increase

We have reviewed the figures we have used over the past several years to calculate AD costs to operators. To account for various inflationary costs in the airline industry, we find it necessary to increase the labor rate used in these calculations from $60 per work hour to $65 per work hour. The cost impact information, below, reflects this increase in the specified hourly labor rate.

Cost Impact

There are about 53 airplanes of U.S. registry that would be affected by this proposed AD.

The AFM revision currently required by AD 95-04-51 takes about 1 work hour per airplane to accomplish, at an average labor rate of $65 per work hour. Based on these figures, the cost impact of the currently required AFM revision is estimated to be $65 per airplane.

The inspections currently required by AD 95-04-51 take about 1 work hour per airplane to accomplish, at an average labor rate of $65 per work hour. Based on these figures, the cost impact of the currently required inspections are estimated to be $65 per airplane, per inspection cycle.

The replacement currently required by AD 95-04-51 takes about 5 work hours per airplane to accomplish, at an average labor rate of $65 per work hour. Required parts will cost about $55,000 per airplane. Based on these figures, the cost impact of the currently required replacement is estimated to be $55,325 per airplane.

The modification proposed in this AD action would take about 10 work hours per airplane to accomplish, at an average labor rate of $65 per work hour. Required parts would be free of charge. Based on these figures, the cost impact of the proposed modification on U.S. operators is estimated to be $34,450, or $650 per airplane.

The inspection/debonding/delamination and leakage inspection proposed in this AD action would take about 1 work hour per airplane to accomplish, at an average labor rate of $65 per work hour. Based on these figures, the cost impact of the proposed inspection on U.S. operators is estimated to be $3,445, or $65 per airplane, per inspection cycle.

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 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.

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.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

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:

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.