AD 97-15-12

This amendment adopts a new airworthiness directive (AD) that applies to certain Burkhart Grob, Luft-und Raumfahrt (Grob) Model G 109 sailplanes. This action requires installing a damper and new bell crank lever on the rudder, in addition to adjusting the weight and balance of the sailplane, to correct the tendency of flutter at specific excitation frequencies. For those Grob Model G 109 sailplanes that have previously accomplished this installation, a modification to the damper and bell crank lever, and adjustment to the weight and balance is required. These actions are prompted by the discovery of rudder vibration problems during testing of two Grob Model G 109 sailplanes. The actions specified by this AD are intended to prevent vibration of the rudder, which could result in structural damage and eventual loss of control of the sailplane.

Final rule

97-15-12 BURKHART GROB, LUFT-UND RAUMFAHRT: Amendment 39-10086; Docket No. 95-CE-03-AD.

Applicability: Model G 109 sailplanes (serial numbers 6001 through 6159), certificated in any category.

NOTE 1: This AD applies to each sailplane 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 sailplanes 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 (e) 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 6 calendar monthsafter the effective date of this AD, unless already accomplished.

To prevent vibration of the rudder, which could result in structural damage and eventual loss of control of the sailplane, accomplish the following:

(a) For sailplanes that have been modified in accordance with Grob Installation Instructions No. 817-38, dated October 25, 1994, per Grob Service Bulletin (SB) TM 817-38, dated July 8, 1993, modify the damper unit and the rudder bell crank lever in accordance with Grob Installation Instructions No. 817-38/1, dated March 31, 1995, per Grob SB 817-38/2, dated March 31, 1995.

(b) For sailplanes that have not been modified in accordance with Grob Installation Instructions No. 817-38, install a new damper unit and rudder bell crank lever in accordance with Grob Installation Instructions 817-38/2 dated March 31, 1995, per Grob SB 817-38/2, dated March 31, 1995.

(c) For all affected sailplanes, re-calculate the weight and balance data in accordance with the Weight and Balance section in Grob SB 817-38/2, dated March 31, 1995.

(d) 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.

(e) 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, Aircraft Certification Service, 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.

(f) The modifications and installations required by this AD shall be done in accordance with GROB, Luft-und Raumfahrt GROB G 109 Installation Instructions No. 817-38 for Service Bulletin TM 817-38, dated October 25, 1994; GROB, Luft-und Raumfahrt GROB G 109 Service Bulletin TM 817-38, dated July 8, 1993; GROB, Luft-und Raumfahrt GROB G 109 Installation Instructions No. 817-38/1 for Service Bulletin 817-38/2, dated March 31, 1995; GROB, Luft-und Raumfahrt GROB G 109 Installation Instructions No. 817-38/2 for Service Bulletin 817-38/2, dated March 31, 1995; and GROB, Luft-und Raumfahrt GROB G 109 Service Bulletin 817-38/2, dated March 31, 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 of this document may be obtained Burkhart Grob Luft-und Raumfahrt, D-86874 Mattsies, Germany. Copies of this document may be inspected at the FAA, Central Region, Office of the Assistant Chief 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.

(g) This amendment becomes effective on September 19, 1997.

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 109 sailplanes was published in the Federal Register on August 30, 1996 (61 FR 45912). The action proposed to require installing a rudder damper and a new rudder bell crank lever in the controls and adjusting the weight and balance; or modifying the rudder damper and bell crank lever, in addition to adjusting the weight and balance of the sailplane.
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.

Related Service Information
Accomplishment of the proposed actions would be in accordance with Grob Service Bulletin (SB) TM 817-38, dated July 8, 1993, Grob SB 817-38/2, dated March 31, 1995, Grob Installation Instructions No. 817-38/1 for Service Bulletin 817-38/2, dated March 31, 1995, Grob Installation Instructions 817-38/2 for Service Bulletin/2, dated March 31, 1995.

The FAA's Determination
After careful review of all available information related to the subject presented above, including the above referenced service information, 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.
Determination of Compliance Time
The compliance time of this AD is in calendar time instead of hours time-in-service (TIS). The average monthly usage of the affected sailplanes ranges throughout the fleet. For example, one owner may operate the sailplane 25 hours TIS in one week, while another operator may operate the sailplane 25 hours TIS in one year. In order to ensure that all of the affected sailplanes have a rudder damper and a new rudder bell crank lever installed within a reasonable amount of time, the FAA is requiring a compliance time of 6 calendar months.
Cost Impact
The FAA estimates that 34 sailplanes in the U.S. registry will be affected by this AD, that it will take approximately 8 workhours per sailplane to accomplish these actions, and that the average labor rate is approximately $60 an hour. Parts cost approximately $1,000 per sailplane. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $50,320. Grob has informed the FAA that no parts have been distributed to equip any sailplane in the United States. The FAA has no way of determining how many owners/operators may have incorporated these actions on their sailplanes.
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 USC 106(g), 40113, 44701.

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