Federal Aviation Administration, DOT.
This amendment adopts a new airworthiness directive (AD) for specified MD Helicopters, Inc. (MDHI) helicopters with a tailboom modified according to Aerometals Supplemental Type Certificate (STC) SH5055NM or SH4801NM. This AD requires an inspection to identify the part number (P/N) of the bolts that attach the tail rotor gearbox to the tailboom and replacing any bolt of inadequate grip length with an airworthy bolt. This AD also requires determining the number of bolt threads protruding from each nutplate and adding an additional washer if more than four threads protrude. This amendment is prompted by the discovery that bolts of inadequate grip length were specified to attach the tail rotor gearbox to the tailboom. The actions specified by this AD are intended to prevent loss of a tail rotor gearbox due to attaching bolts of inadequate grip length and subsequent loss of control of the helicopter.
Effective August 1, 2002.Start Further Info
FOR FURTHER INFORMATION CONTACT:
John Cecil, Aviation Safety Engineer, FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 Paramount Blvd., Lakewood, California 90712-4137, telephone (562) 627-5228, fax (562) 627-5210.End Further Info End Preamble Start Supplemental Information
A proposal to amend 14 CFR part 39 to include an AD for the specified MDHI helicopters was published in the Federal Register on December 27, 2001 (66 FR 66821). That action proposed requiring the following:
- Identifying the P/N of the bolts that attach the tail rotor gearbox to the tailboom;
- Replacing any bolt that is not a NAS1304-26 part-numbered bolt with a NAS1304-26 bolt;
- Replacing any bolt of inadequate grip length; and
- Determining the number of bolt threads protruding from each nutplate Start Printed Page 43228and adding an additional washer if more than four threads protrude.
Aerometals issued Service Bulletin SB-001, dated August 3, 2000 (SB), which describes procedures for verifying that the proper attaching bolts are used to install the tail rotor gearbox to the tailboom.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comment received.
The one commenter states that the applicability of the AD should be limited to certain part-numbered tailbooms with serial number (S/N) 5001-5032 specified in the FAA-approved Aerometals SB. The FAA disagrees because the specified tailbooms, S/N 5001-5032, installed with the affected bolts, may not have remained on the same helicopters. Any of the helicopters listed in the proposed AD may have had bolts with inadequate grip length installed per Aerometals STC SH5055NM or SH4801NM and must be inspected and, if required, modified.
After careful review of the available data, including the comment noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed. However, we have added introductory language for Figure 1 and placed Figure 1 directly after the AD paragraph in which it is referenced. We have determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.
The FAA estimates that this AD will:
- Affect 500 helicopters of U.S. registry;
- Require 1/2 work hour per helicopter to determine whether a helicopter has been modified by either STC; and
- Require 1 work hour to inspect and replace the bolts for each of approximately 40 helicopters modified by the STC's.
The average labor rate is $60 per work hour. Required parts will cost approximately $40 per helicopter. Based on these figures, we estimate the total cost impact of the AD on U.S. operators to be $19,000.
The regulations adopted herein will not have a substantial direct effect 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, it is determined that this final rule does not have federalism implications under Executive Order 13132.
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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas.Start List of Subjects
List of Subjects in 14 CFR Part 39End List of Subjects
Adoption of the AmendmentStart Amendment Part
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (End Amendment Part Start Part
PART 39—AIRWORTHINESS DIRECTIVESEnd Part Start Amendment Part
1. The authority citation for part 39 continues to read as follows:End Amendment Part
2. Section 39.13 is amended by adding a new airworthiness directive to read as follows:End Amendment Part
2002-13-05 MD Helicopters, Inc.: Amendment 39-12793. Docket No. 2001-SW-40-AD.
Applicability: Model 369D, 369E, 369F, and 369FF helicopters, modified in accordance with Aerometals Supplemental Type Certificate (STC) SH5055NM or SH4801NM, certificated in any category.
This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise 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 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, unless accomplished previously.
To prevent loss of the tail rotor gearbox due to attaching bolts of inadequate grip length and subsequent loss of helicopter control, accomplish the following:
(a) Within 25 hours time-in-service (TIS), conduct the following inspections:
(1) For each tail rotor gearbox attaching bolt (bolt):
(i) Determine the part number (P/N).
(ii) If the P/N cannot be determined or if the bolt is not P/N NAS1304-26, before further flight, replace the bolt with bolt, P/N NAS1304-26.
(iii) Torque the bolt to 100-110 in-lbs and apply a slippage mark.
(2) Remove the tailboom control rod and determine the number of bolt threads protruding from each nutplate on the internal surface of the aft tailboom frame casting, P/N 369D23503, as shown in Figure 1 of this AD. At least one thread must protrude. If more than four threads protrude, add an additional washer, P/N AN960D416, under the bolt head. Torque the bolt to 100-110 in-lbs, and reapply a slippage mark. See Figure 1:Start Printed Page 43229
(b) Between 2 and 10 hours TIS after accomplishing the requirements of paragraph (a) of this AD, inspect the torque on each bolt by applying 100 in-lbs. If any bolt movement occurs, retorque the bolt to 100-110 in-lbs and reapply a slippage mark. Reinspect the torque between 2 and 10 hours TIS thereafter until no bolt movement occurs.
Aerometals Service Bulletin SB-001, dated August 3, 2000, pertains to the subject of this AD.
(c) 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, Los Angeles Aircraft Certification Office (LAACO), FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, LAACO.
Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the LAACO.
(d) Special flight permits will not be issued.
(e) This amendment becomes effective on August 1, 2002.Start Signature
Issued in Fort Worth, Texas, on June 18, 2002.
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
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[FR Doc. 02-16057 Filed 6-26-02; 8:45 am]
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