AD 98-24-09

This amendment adopts a new airworthiness directive (AD) that applies to certain Burkhart GROB Luft-und Raumfahrt GmbH (Grob) Model G 109B gliders. This AD requires inspecting the elevator and trim tab for water, and assuring that the necessary drain holes are installed and existing drain holes are open. This AD also requires drilling any necessary drain holes and opening any existing drain holes that are closed; and, if a significant amount of water (more than 1/2 liter) is found in the elevator, assuring that the elevator ;s weight and residual momentum and the glider s center of gravity (C.G.) are within the limits specified in the flight manual, and adjusting the elevator s weight and residual momentum and the glider s C.G., as needed. 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 water from penetrating the elevator and trim tab because of inadequate drainage, which could result in a delaminated elevator and trim tab structure with consequent elevator imbalance and flutter.

Final rule

98-24-09 BURKHART GROB LUFT-UND RAUMFAHRT GMBH: Amendment 39-10895; Docket No. 98-CE-71-AD.

Applicability: Model G 109B gliders, all serial numbers beginning with 6200, 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 (c) 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 in the body of this AD, unless already accomplished.

To prevent water from penetrating the elevator and trim tab because of inadequate drainage, which could result in a delaminated elevator and trim tab structure with consequent elevator imbalance and flutter, accomplish the following:

(a) Within the next 6 calendar months after the effective date of this AD, inspect the elevator and trim tab for water and to assure that the necessary drain holes are installed and that the existing drain holes are open. Accomplish these actions in accordance with the Actions section of Grob Service Bulletin TM 817-35, dated July 20, 1992. Prior to further flight after the inspection, accomplish the following as specified in the service bulletin:

(1) Drill any necessary drain holes and open any existing drain holes that are closed; and,

(2) If a significant amount of water (more than 1/2 liter) is found in the elevator, after removal of the water, assure that the elevator's weight and residual momentum and the glider's center of gravity (C.G.) are within the limits specified in the flight manual, and adjust the elevator's weight and residual momentum and the glider's C.G., as needed.

(b) 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.

(c) 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, 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 AirplaneDirectorate.

(d) Questions or technical information related to Grob Service Bulletin TM 817-35, dated July 20, 1992, should be directed to Burkhart Grob Luft-und Raumfahrt, D-8939 Mattsies, Germany. 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.

(e) The inspections and modifications required by this AD shall be done in accordance with Grob Service Bulletin TM 817-35, dated July 20, 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 Burkhart Grob Luft-und Raumfahrt, D- 8939 Mattsies, 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 92-350 Grob, dated October 26, 1992.

(f) This amendment becomes effective on December 28, 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 certain Grob Model G 109B gliders was published in the Federal Register as a notice of proposed rulemaking (NPRM) on September 17, 1998 (63 FR 49673). The NPRM proposed to require inspecting the elevator and trim tab for water, and assuring that the necessary drain holes are installed and existing drain holes are open. The NPRM also proposed to require drilling any necessary drain holes and opening any existing drain holes that are closed; and, if a significant amount of water (more than 1/2 liter) is found in the elevator, assuring that the elevator s weight and residual momentum and the glider s center of gravity (C.G.) are within the limits specified in the flight manual, and adjusting the elevator s weight and residual momentum and the glider s C.G., as needed. Accomplishment of the proposed action as specified in the NPRM would be in accordance with Grob Service Bulletin TM 817-35, dated July 20, 1992.

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

Cost Impact
The FAA estimates that 20 gliders in the U.S. registry will be affected by this AD, that it will take approximately 1 workhour per glider to accomplish the proposed inspection, and that the average labor rate is approximately $60 an hour. Based on these figures, the total cost impact of the inspection on U.S. operators is estimated to be $1,200, or $60 per glider.

If drain holes need to be added, the FAA estimates that it will take approximately 1 workhour per glider to accomplish the modification, and that the average labor rate is approximately $60 an hour. Based on these figures, the total cost impact of the modification on U.S. operators is estimated to be $60 per glider that will need drain holes installed.

Compliance Time of this AD
The compliance time of this AD is presented in calendar time instead of hours time-in-service (TIS). The unsafe condition is not a result of the number of times the glider is operated. If the elevator and trim tab of the affected gliders have inadequate drainage, then watercould penetrate the elevator and trim tab on the first flight, as well as subsequent flights. The delamination and imbalance that could then occur can happen in a very short period of time or happen over a long period of time. For these reasons, 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.

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 nota " 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: