On October 12, 1999, the FAA issued Emergency Priority Letter AD 99-22-01, applicable to ECD Model EC135 P1 and T1 helicopters, which requires, before further flight and at specified time intervals until an additional bearing support bracket is installed on the frame flange, inspecting and replacing, if necessary, the frame flange. The AD also requires, within 7 days, adding the additional bearing support bracket to the frame flange. Thereafter, the AD requires visually inspecting the frame flange for cracks or misalignment of the slippage marks at specified time intervals. That action was prompted by the discovery of a crack in the frame flange at the attachment points of the tail rotor drive shaft bearing support. The crack, discovered during an inspection of an ECD Model EC135 helicopter, was caused by metal fatigue due to unanticipated loads at this location. This condition, if not corrected, could result in a fracture of the bearing frame flange,failure of the tail rotor drive shaft, and subsequent loss of control of the helicopter.
The Luftfahrt-Bundesamt (LBA), which is the airworthiness authority for the Federal Republic of Germany, notified the FAA that an unsafe condition may exist on ECD Model EC135 P1 and T1 helicopters, serial numbers (S/N) 0005 through 0120. The LBA issued AD 1999-199/3, dated October 5, 1999, applicable to ECD Model EC135 helicopters, S/N 0005 through 0120. The LBA advises that during an inspection a crack was detected on the frame flange of the tail rotor drive shaft bearing support.
The FAA has reviewed ECD Alert Service Bulletins EC 135-53A-009, dated March 23, 1999, and EC 135-53A-010, Revision 2, dated July 22, 1999 (ASB). The ASB's describe procedures for conducting a dye-penetrant crack inspection before further flight and conducting repetitive inspections at intervals not to exceed 15 hours time-in-service (TIS) until the helicopters are fitted with an additional bearing supportbracket at bearing location I as identified in the ASB's. ASB EC 135-53A-010, Revision 2, also defines the 50-hour repetitive inspection necessary after the modification is accomplished.
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 ECD Model EC135 P1 and T1 helicopters of the same type design, the FAA issued Emergency Priority Letter AD 99-22-01 to prevent a fracture of the bearing frame flange, failure of the tail rotor drive shaft, and subsequent loss of control of the helicopter. The AD requires, before further flight, conducting a dye-penetrant inspection of the tail boom frame flange at the attachment points of the tail rotor drive shaft bearing as shown in location I in Figure 1 of the ASB's. If a crack is found, the AD requires replacing the tail boom frame flange before further flight. The dye-penetrant inspection of the frame flange is required at intervals not to exceed 15 hours TIS until an additional bearing support bracket has been installed. The AD also requires, within 7 days, modifying the frame flange by installing an additional bearing support bracket. After modifying the frame flange, a visual inspection for a crack or for misalignment of the slippage marks is to be conducted at intervals not to exceed 50 hours TIS. The actions must be accomplished in accordance with the ASB's described previously. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the structural integrity of the helicopter. Therefore, inspecting and replacing, if necessary, the frame flange is required before further flight; modifying the frame flange is required within 7 days; and inspecting the modified frame flange is required at 50 hour TIS intervals; 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 October 12, 1999 to all known U.S. owners and operators of ECD Model EC135 P1 and T1 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 14 helicopters of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per helicopter to accomplish the dye-penetrant inspections, 48 work hours per helicopter to replace the frame flange, if necessary, and 3 work hours per helicopter to install the additional bearing support bracket on the frame flange. The average labor rate is $60 per work hour. The manufacturer has stated that required parts will be provided at no cost. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $24,360, assuming conducting one dye-penetrant inspection on each helicopter, replacing the frame flange in half the fleet, and modifying the frame flange in all the 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. 99-SW-59-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, 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 to read as follows: