[Federal Register Volume 62, Number 33 (Wednesday, February 19, 1997)] [Proposed Rules] [Pages 7373-7375] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 97-3961] ======================================================================= ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 96-CE-40-AD] RIN 2120-AA64 Airworthiness Directives; Grob Luft-und Raumfahrt, GmbH; Models G 109 and G 109B Sailplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Grob Luft-und Raumfahrt (Grob) Models G 109 and G 109B sailplanes. The proposed action would require inspecting the landing gear retaining bars and landing gear legs for proper radius, thickness, and cracking, and installing additional supportive parts or replacing the retaining bars and landing legs with parts of improved design. Reports of landing gear failure on certain G 109 and G 109B sailplanes prompted the proposed action. The actions specified by the proposed AD are intended to prevent failure of the landing gear legs and possible loss of the sailplane. DATES: Comments must be received on or before April 21, 1997. ADDRESSES: Submit comments on the proposal in triplicate to the Federal Aviation Administration (FAA), Central Region, Office of the Assistant Chief Counsel, Attention: Rules Docket No. 96-CE-40-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Comments may be inspected at this location between 8 a.m. and 4 p.m., Monday through Friday, holidays excepted. Service information that applies to the proposed AD may be obtained from Grob Luft-und Raumfahrt, GmbH., D-8939, Mattsies-am Flugplatz, Germany. This information also may be examined at the Rules Docket at the address above. FOR FURTHER INFORMATION CONTACT: Mr. J. Mike Kiesov, Project Officer, Sailplanes, FAA, Small Airplane Directorate, 1201 Walnut, suite 900, Kansas City, Missouri 64106; telephone (816) 426-6932; facsimile (816) 426-2169. 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 should 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 notice may be changed in light of the comments received. 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 that summarizes 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket No. 96-CE-40-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, Central Region, Office of the Assistant Chief Counsel, Attention: Rules Docket No. 96-CE-40-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Discussion The Luftfahrt-Bundesamt (LBA), which is the airworthiness authority for Germany, recently notified the FAA that an unsafe condition may exist on certain Grob G 109 and G 109B sailplanes. The LBA reports that the landing gear on three of these sailplanes failed during landing. An investigation of these incidents revealed landing gear legs with fatigue cracks and weak retaining bars from an error in the manufacturing process. This condition, if not detected and corrected, could result in landing gear failure and possible loss of the sailplane. Related Service Information Grob has issued Service Bulletin TM 817-39, dated January 4, 1994, which specifies procedures for inspecting and modifying or replacing the landing gear retaining bars and the landing gear legs. The landing gear retaining bar should have a minimum radius of 3.0 millimeters (mm) on the chamfer. If the [[Page 7374]] radius is less than 3.0 mm, the retaining bar would be replaced with an improved retaining bar (part number (P/N) 109-5000.02) and a plastic reinforcing strip (P/N 109-5000.07). If the radius is 3.0 mm or greater, the plastic reinforcing strip would be glued onto the retaining bars. The landing gear legs that are not marked with ``0'' (zero) would require inspecting for cracks by the magnetic particle or x-ray method, and if there are any cracks measuring greater than 0.5 mm, the landing gear legs would be replaced with new legs. If there are cracks measuring less than 0.5 mm, the proposed action would require polishing the cracks out, unless polishing would reduce the total leg thickness to less than 13.0 mm. If the leg thickness is less than 13.0 mm, the landing gear leg would be replaced. If there are no cracks in the landing gear legs, or the landing gear leg thickness is greater than 13.0 mm, after polishing, the proposed action would require repetitively inspecting until cracks are found, or until new landing gear legs are installed. Installing the improved landing gear legs and the improved retaining bars would terminate the proposed repetitive inspection. The LBA classified this service bulletin as mandatory and issued AD 94-004/2 Grob, dated February 3, 1994, in order to ensure the continued airworthiness of these sailplanes in Germany. FAA's Determination These sailplane models are manufactured in Germany and are 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 the FAA informed of the situation described above. The FAA has examined the findings of the LBA, reviewed all available information including the service information referenced above, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States. Explanation of the Provisions of the Proposed AD Since an unsafe condition has been identified that is likely to exist or develop in other Grob G 109 and G 109B sailplanes of the same type design registered in the United States, the proposed AD would require: (1) Inspecting the retaining bars chamfer for the correct radius, and replacing the bars or reinforcing the bars, as applicable. (2) Inspecting the landing gear legs that are not marked with ``0'' (zero) on the front of the legs for fatigue cracks, and if cracks are greater than or less than the tolerance measurement, either replace or repetitively inspect the landing gear legs, as applicable. (3) Measure the total thickness of the landing gear legs. If they measure less than, greater than or equal to 13.0 mm, continue to inspect or replace legs with new improved legs, as applicable. (4) Replacing the landing gear legs with parts of improved design would terminate the proposed repetitive inspections. Cost Impact The FAA estimates that 63 sailplanes in the U.S. registry would be affected by the proposed AD, that it would take approximately 2 workhours per leg per sailplane to accomplish the inspection and modification on the proposed retaining bar action, approximately 9 workhours per leg per sailplane to accomplish the removal, inspection and re-installation, and approximately 6 workhours per leg to accomplish the replacement. The average labor rate is approximately $60 an hour. Parts cost approximately $90 per sailplane for retaining bars and $1800 per sailplane for landing gear legs. The plastic strip for the retaining bar is provided by the manufacturer at no charge. Breaking these costs down by individual action, the estimated total cost for each action would be as follows: --The proposed inspection and modification of the retaining bars would be $210 ($120/labor + $90/parts) per sailplane or $13,230 for the U.S. fleet. --The proposed inspection and polishing of the landing gear legs would be $540 per sailplane or $34,020 for the U.S. fleet. --The proposed replacement of the landing gear legs would be $2,160 ($360/labor + $1,800/parts) per sailplane or $136,080 for the U.S. fleet. --The cost for the proposed repetitive inspections on the landing gear legs is not included in the above figures. The manufacturer has informed the FAA that they have dispatched equipment to outfit approximately 30 sailplanes with new retaining bars, reducing the estimated cost impact of the retaining bars from $13,230 to $6,930. The manufacturer has also distributed approximately 3 sets of new landing gear legs, reducing the estimated total cost impact of the landing gear leg replacement from $136,080 to $129,600. Proposed Compliance Time The compliance time of the proposed AD is presented in calendar time instead of hours time-in-service (TIS). The FAA has determined that a calendar time compliance is the most desirable method because the unsafe condition of the landing gear legs described by this AD is caused by corrosion. Corrosion initiates as a result of sailplane operation, but can continue to develop regardless of whether the sailplane is in service or in storage. Therefore, to ensure that the above-referenced condition is detected and corrected on all sailplanes within a reasonable period of time without inadvertently grounding any sailplanes, a compliance schedule based upon calendar time instead of hours TIS is required. Regulatory Impact The regulations proposed herein would 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 proposal would 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) 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 has been placed 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: [[Page 7375]] PART 39--AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 USC 106(g), 40113, 44701. Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: Grob Luft-Und Raumfahrt, GMBH. (GROB): Docket No. 96-CE-40-AD. Applicability: Models G 109 and G 109B sailplanes, all serial numbers, 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 as indicated in the body of this AD, unless already accomplished. To prevent failure of the landing gear legs and possible loss of the sailplane, accomplish the following: (a) Within the next 120 calendar days after the effective date of this AD, inspect the retaining bars chamfer on both landing gear legs for a minimum of 3.0 millimeters (mm) radius in accordance with the ``Actions'' section, paragraph A3 in Grob Service Bulletin (SB) 817-39, dated January 4, 1994. (1) If the chamfer radius is 3.0 mm or greater, prior to further flight, glue a reinforcing plastic strip (part number (P/N) 109- 5000.07) to the retaining bar in accordance with the ``Actions'' section, paragraph A4 in Grob SB 817-39, dated January 4, 1994. (2) If the chamfer radius is less than 3.0 mm, prior to further flight, replace with a new improved retaining bar (P/N 109-5000.02), and install the plastic strip (P/N 109-5000.07) in accordance with the ``Actions'' section, paragraph A5 in Grob SB 817-39, dated January 1994. (b) For sailplanes not equipped with landing gear legs, P/N 109B-5001.01/1, within the next 2,000 sailplane landings or 1,000 hours TIS after the effective date, whichever occurs first, inspect the landing gear legs for cracks (using the magnetic particle or X- ray analysis method) in accordance with the ``Actions'' section, paragraph B9 in Grob SB 817-39, dated January 4, 1994. Note 2: Landing gear legs (P/N 109B-5001.01/1) have a ``0'' stamped on the front side of the leg for easy identification. (1) If there are cracks less than or equal to 0.5 mm, prior to further flight, polish the existing legs or replace the legs with P/ N 109B-5001.01/1 in accordance with the ``Actions'' section, paragraph B10 in Grob SB 817-39, dated January 4, 1994. (2) If the polished landing gear legs measures less than 13.0 mm, prior to further flight, replace the landing gear legs with P/N 1090B-5001.01/1 in accordance with the ``Actions'' section, paragraph B10 in Grob SB 817-39, dated January 4, 1994. (3) If no cracks are found, or the cracks are less than 0.5 mm, and the thickness of the landing gear legs is equal to or greater than 13.0 mm, repetitively inspect the landing gear legs for cracks every 1,000 landings or 500 hours TIS, whichever occurs first, in accordance with the ``Actions'' section, paragraph B12 in Grob SB 817-39, dated January 4, 1994. (4) If during any of the repetitive inspections, the legs have previously been polished and new cracks are found, prior to further flight, replace the legs with P/N 109B-5001.01/1 in accordance with the ``Actions'' section, paragraph B12 in Grob SB 817-39, dated January 4, 1994. (c) Replacement of the landing gear legs with P/N 109B-5000.01/1 terminates the repetitive inspections required by this AD and Grob SB 817-39, dated January 4, 1994. (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 sailplane to a location where the requirements of this AD can be accomplished. (e) An alternative method of compliance or adjustment of the initial or repetitive compliance times 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 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Small Airplane Directorate. (f) All persons affected by this directive may obtain copies of the documents referred to herein upon request to Grob Luft-und Raumfahrt, GmbH., D-8939, Mattsies-am Flugplatz, Germany or may examine these documents at the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Issued in Kansas City, Missouri, on February 10, 1997. Henry A. Armstrong, Acting Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. 97-3961 Filed 2-18-97; 8:45 am] BILLING CODE 4910-13-U