AD 98-12-04

This amendment adopts a new airworthiness directive (AD) that applies to all Glaser-Dirks Flugzeugbau GmbH (Glaser-Dirks) Model DG-500M gliders. This AD requires installing a rudder gap seal and modifying the cooling liquid reservoir mount. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Germany. The actions specified by this AD are intended to prevent rudder vibrations caused by flow separation at the rudder gap, which could result in flutter with consequent loss of rudder control.

Final rule

98-12-04 GLASER-DIRKS FLUGZEUGBAU GMBH: Amendment 39-10561; Docket No. 98-CE-09-AD.
Applicability: Model DG-500M gliders, all serial numbers, certificated in any category.

NOTE 1: This AD applies to each glider 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 gliders 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 within the next 3 calendar months after the effective dateof this AD, unless already accomplished.

To prevent rudder vibrations caused by flow separation at the rudder gap, which could result in flutter with consequent loss of rudder control, accomplish the following:

(a) Install a rudder gap seal in accordance with the instructions in the maintenance manual, as referenced in Glaser-Dirks Technical Note (TN) No. 843/5, dated November 30, 1992.

(b) Modify the cooling liquid reservoir mount in accordance with Glaser-Dirks Working Instruction No. 1 for TN 843/5, dated November 5, 1992, as referenced in Glaser-Dirks TN No. 843/5, dated November 30, 1992.

(c) 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 glider to a location where the requirements of this AD can be accomplished.

(d) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be approved by the Manager, Small Airplane Directorate, FAA, 1201 Walnut, suite 900, Kansas City, Missouri 64106. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Small Airplane Directorate.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Small Airplane Directorate.

(e) Questions or technical information related to Glaser-Dirks Technical Note No. 843/5, dated November 30, 1992, should be directed to DG Flugzeugbau GmbH, Postfach 4120, D-76625 Bruchsal 4, Germany; telephone: +49 7257-89-0; facsimile: +49 7257-8922. This service information may be examined at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

(f) The modification required by this AD shall be done in accordance with Glaser-Dirks Working Instruction No. 1 for Technical Note 843/5, dated November 5, 1992, as referenced in Glaser-Dirks Technical Note No. 843/5, dated November 30, 1992. 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 DG Flugzeugbau GmbH, Postfach 4120, D-76625 Bruchsal 4, Germany. Copies may be inspected at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

NOTE 3: The subject of this AD is addressed in German AD 93-010, dated January 5, 1993.

(g) This amendment becomes effective on July 21, 1998.

Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all Glaser-Dirks Model DG-500M gliders was published in the Federal Register as a notice of proposed rulemaking (NPRM) on March 20, 1998 (63 FR 13581). The NPRM proposed to require installing a rudder gap seal and modifying the cooling liquid reservoir mount. Accomplishment of the proposed installation as specified in the NPRM would be required in accordance with the maintenance manual. Accomplishment of the proposed modification to the cooling liquid reservoir mount as specified in the NPRM would be required in accordance with Glaser-Dirks Working Instruction No. 1 for TN 843/5, dated November 5, 1992, as referenced in Glaser-Dirks TN No. 843/5, dated November 30, 1992.

The NPRM was the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authorityfor Germany.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposed rule or the FAA's determination of the cost to the public.

The FAA's Determination
After careful review of all available information related to the subject presented above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. The FAA has determined that these minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.

Compliance Time of This AD
Although the rudder vibrations identified in this AD occur during flight, this unsafe condition is not a result of the number of times the glider is operated. The chance of this situation occurring is the same for a glider with 10 hours time-in-service (TIS) as it is for a glider with 500 hours TIS. For this reason, the FAA has determined that a compliance based on calendar time should be utilized in this AD in order to assure that the unsafe condition is addressed on all gliders in a reasonable time period.

Cost Impact
The FAA estimates that 5 gliders in the U.S. registry will be affected by this AD, that it will take approximately 4 workhours per glider to accomplish this action, and that the average labor rate is approximately $60 an hour. Parts cost approximately $40 per glider. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $1,400, or $280 per glider.

Regulatory Impact
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.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under 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. A copy of the final 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, 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 U.S.C. 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: