# AD 98-09-11: Airworthiness Directives; Eurocopter Deutschland GmbH Model EC 135 Helicopters - Type: Airworthiness directive - Effective: July 13, 1998 - Published: June 26, 1998, 63 FR 34796–34798 - Issued as: Final rule; request for comments - Superseded by: Nothing supersedes this AD - Amendment: 39-10632 - Docket: 98-SW-18-AD - Official PDF: https://openairdocs.org/files/sha256/4e/0b/4e0b64f041806545b374db5e8633f12bc73e5c1a5919dda8da290643f4a78de6 (from https://www.govinfo.gov/content/pkg/FR-1998-06-26/pdf/98-17023.pdf) - Federal Register: https://www.federalregister.gov/documents/1998/06/26/98-17023/airworthiness-directives-eurocopter-deutschland-gmbh-model-ec-135-helicopters - Page: https://openairdocs.org/ad/98-09-11 ## Summary This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 98-09-11 which was sent previously to all known U.S. owners and operators of Eurocopter Deutschland GmbH (Eurocopter) Model EC 135 helicopters by individual letters. This AD requires, before further flight, a review of aircraft records to determine if a tail rotor drive shaft vibration survey and installation of a Fenestron Shaft Retrofit Kit have been accomplished; before further flight, and thereafter at intervals not to exceed 15 hours time-in-service, inspecting the tail rotor drive shaft bearing (bearing) attaching lock plates for bent-open tabs, and broken or missing slippage marks; and visually inspecting each bearing support for cracks. This amendment is prompted by three reports of loose bearings and attachment bolts, and one report of a cracked bearing support. Excessive vibrations in the tail rotor drive shaft can loosen attachment bolts or cause cracking in the bearing supports. This condition, if not corrected, could result in loss of drive to the tail rotor and subsequent loss of control of the helicopter. ## The airworthiness directive ### 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. ### Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: AD 98-09-11 Eurocopter Deutschland GmbH: Amendment 39-10632. Docket No. 98-SW-18-AD. Applicability: Model EC 135 helicopters, serial numbers 0005 through 0048, certificated in any category. Note 1: This AD applies to each helicopter 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 helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must use the authority provided in paragraph (d) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any helicopter from the applicability of this AD. Compliance: Required as indicated, unless accomplished previously. To detect loose tail rotor drive shaft bearing (bearing) attachment bolts, or cracked bearing supports, which could result in loss of drive to the tail rotor and subsequent loss of control of the helicopter, accomplish the following: ### (a) (a) Before further flight, review the helicopter's historical records to determine if a tail rotor drive shaft vibration survey and the installation of Fenestron Shaft Retrofit Kit L 535M3002 882 have been accomplished. If either action has not been accomplished, contact the Manager, Rotorcraft Standards Staff, FAA, telephone (817) 222-5110, fax (817) 222-5961. ### (b) (b) Before further flight, and thereafter at intervals not to exceed 15 hours time-in-service (TIS), at each bearing support: (1) Inspect each bearing attaching lock plate that was installed with the Fenestron Shaft Retrofit Kit L 535M3002 882 for bent-open tabs. (2) Inspect for broken or missing slippage marks that may indicate looseness or rotation of attaching hardware. (3) If a lock plate tab is bent open on bearing supports A, B, or C (shown in Figure 1), or if slippage marks are broken or missing, contact the Manager, Rotorcraft Standards Staff. [graphic omitted; see the official PDF] ### (c) (c) Before further flight, and thereafter at intervals not to exceed 15 hours TIS, using a 6-power or higher magnifying glass and a bright light, visually inspect bearing supports B and C as shown in Figure 1 for cracks. If a crack is found, replace the bearing support with an airworthy bearing support. ### (d) (d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Rotorcraft Standards Staff, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Standards Staff. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Rotorcraft Standards Staff. ### (e) (e) Special flight permits will not be issued. ### (f) (f) This amendment becomes effective on July 13, 1998, to all persons except those persons to whom it was made immediately effective by Priority Letter AD 98-09-11, issued April 17, 1998, which contained the requirements of this amendment. Note 3: The subject of this AD is addressed in Luftfahrt-Bundesamt (Federal Republic of Germany) AD 1998-033/5, dated April 6, 1998. Issued in Fort Worth, Texas, on June 18, 1998. Eric Bries, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. ## Rule preamble ### Dates Effective July 13, 1998, to all persons except those persons to whom it was made immediately effective by priority letter AD 98-09-11, issued on April 17, 1998, which contained the requirements of this amendment. Comments for inclusion in the Rules Docket must be received on or before August 25, 1998. ### Addresses Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 98-SW-18-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. ### For further information contact Mr. Scott Horn, Aerospace Engineer, FAA, Rotorcraft Directorate, Rotorcraft Standards Staff, 2601 Meacham Blvd., Fort Worth, Texas 76137, telephone (817) 222-5125, fax (817) 222-5961. ### Supplementary information On April 17, 1998, the FAA issued priority letter AD 98-09-11, applicable to Eurocopter Model EC 135 helicopters, which requires, before further flight, a review of aircraft records to determine if a tail rotor drive shaft vibration survey and installation of a Fenestron Shaft Retrofit Kit L 535M3002 882 have been accomplished. If a tail rotor vibration survey has not been accomplished or if a Fenestron Shaft Retrofit Kit has not been installed, the FAA must be contacted. Also, before further flight, and thereafter at intervals not to exceed 15 hours time-in-service, the AD requires inspecting the bearing attaching lock plates at each bearing support for bent-open tabs, and inspecting for broken or missing slippage marks. If a bearing attaching lock plate tab is bent open, or if a slippage mark is broken or missing, the FAA must be notified. Finally, the AD requires visually inspecting each bearing support for cracks, and if a crack is found, replacing the bearing support with an airworthy bearing support. That action was prompted by three reports of loose bearings and attachment bolts, and one report of a cracked bearing support. Excessive vibrations in the tail rotor drive shaft can loosen attachment bolts or cause cracking in the bearing supports. This condition, if not corrected, could result in loss of drive to the tail rotor and subsequent loss of control of the helicopter. The Luttfahrt-Bundesamt (LBA), which is the airworthiness authority for the Federal Republic of Germany, recently notified the FAA that an unsafe condition may exist on Eurocopter Deutschland GmbH (ECD) Model EC 135 helicopters. The LBA advises that the loosening of bolt connections at the bearing supports may lead to a tail rotor failure and thus to the loss of the helicopter. The LBA issued AD 1998-033/5, dated April 6, 1998, applicable to ECD Model EC 135 helicopters. The FAA has reviewed Eurocopter EC 135 Alert Service Bulletin No. EC 135-53A-002, dated December 12, 1997, which describes procedures for visually inspecting the bearing supports, and Eurocopter EC 135 Alert Service Bulletin No. EC 135-53A-005, Revision 1, dated April 6, 1998, which describes procedures for measuring vibrations on the tail rotor drive shaft and replacement of roller bearing attaching hardware at bearing locations. This helicopter model is manufactured in the Federal Republic of Germany and is type certificated for operation in the United States under the provision 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, and determined that AD action is necessary for products of this type design that are certificated for operations in the United States. Since the unsafe condition described is likely to exist or develop on other Eurocopter Model EC 135 helicopters of the same type design, the FAA issued priority letter AD 98-09-11 to detect loose bearing attachment bolts, or cracked bearing supports, which could result in loss of drive to the tail rotor and subsequent loss of control of the helicopter. The AD requires, before further flight, a review of aircraft records to determine if a tail rotor drive shaft vibration survey and installation of a Fenestron Shaft Retrofit Kit L 535M3002 882 have been accomplished. If a tail rotor vibration survey has not been accomplished or if a Fenestron Shaft Retrofit Kit has not been installed, the FAA must be contacted. Also, before further flight, and thereafter at intervals not to exceed 15 hours time-in-service, the AD requires inspecting the bearing attaching lock plates at each bearing support for bent-open tabs, and inspecting for broken or missing slippage marks. If a bearing attaching lock plate tab is bent open, or if a slippage mark is broken or missing, the FAA must be notified. Finally, the AD requires visually inspecting each bearing support for cracks, and if a crack is found, replacing the bearing support with an airworthy bearing support. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the controllability of the helicopter. Therefore, reviewing aircraft records, inspecting the bearing attaching lock plates, and visually inspecting each bearing support for cracks are required before further flight and this AD must be issued immediately. Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on April 17, 1998 to all known U.S. owners and operators of Eurocopter Model EC 135 helicopters. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons. The FAA estimates that 6 helicopters of U.S. registry will be affected by this AD, that it will take approximately .5 work hour per helicopter to review aircraft records and 1 work hour per helicopter to conduct the required inspections, and that the average labor rate is $60 per work hour. Required parts will be provided at no cost by the manufacturer. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $540 to review the aircraft records and perform the inspections once on each helicopter in the U.S. fleet. ### Comments Invited Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 AD will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket No. 98-SW-18-AD.'' The postcard will be date stamped and returned to the commenter. 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. The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a ``significant regulatory action'' under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from 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. ### 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: No proposed rule in this release led to it. Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.