AD 2008-15-03

This amendment adopts a new airworthiness directive (AD) for MD Helicopters, Inc. (MDHI) Model 369A, OH-6A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, and 369HS helicopters that requires repetitive tap inspections of each tail rotor (T/R) blade abrasion strip. This amendment is prompted by an incident in which an abrasion strip separated from a T/R blade. The actions specified by this AD are intended to prevent disbonding and subsequent separation of an abrasion strip from a T/R blade, which could result in vibration, loss of the T/ R, and subsequent loss of control of the helicopter.

Final rule.

2008-15-03 MD Helicopters, Inc. (MDHI): Amendment 39-15615. Docket No. FAA-2008-0287; Directorate Identifier 2006-SW-15-AD.

Applicability: Model 369A, OH-6A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, and 369HS, certificated in any category, with a tail rotor (T/R) blade installed as follows including all serial numbers and those T/R blades with an "M'' or an "I'' painted on the T/R blade root:
Helicopter Technology Company, LLC (HTC) part number (P/N) 500P3100-101 and -103, or MDHI P/N 369D21640-501, -503, and - 505.
HTC P/N 500P3100-301 and -303, or MDHI P/N 369D21641- 501, -503, and -505.
HTC P/N 500P3300-501 and -503, or MDHI P/N 369D21643- 501, -503, and -505.
HTC P/N 500P3500-701 and -703, or MDHI P/N 369D21642- 501, -503, and -505.

Note 1: An "M'' or an "I'' painted on the root of the T/R blade indicates compliance to an Alternate Method of Compliance (AMOC) to Emergency AD 2003-08-51 (Docket No. 2003-SW-17-AD, Amendment 39-13215, April 15, 2003), issued by the FAA, Los Angeles Aircraft Certification Office (LAACO) on June 13, 2003 to HTC. The AMOC addressed shot peening of the pitch horn of the T/R assembly.

Compliance: Required as indicated.

To prevent disbonding and subsequent separation of an abrasion strip from a T/R blade, which could result in vibration, loss of the T/R, and subsequent loss of control of the helicopter, accomplish the following:

(a) Within 25 hours time-in-service (TIS), unless accomplished previously, and thereafter at intervals not to exceed 25 hours TIS, inspect the abrasion strip-to-skin bond integrity on each T/R blade using a tap test method in accordance with Part 1--Inspection, in Helicopter Technology Company, LLC (HTC) Mandatory Service Bulletin Notice No. 3100-4R4, dated May 10, 2006 (SB).

Note 2: MD Helicopters Service Bulletin SB369D-203R1, SB369E- 097R1, SB369F-082R1, and SB369H-246R1, dated January 23, 2006, pertain to the subject of this AD.

(b) Modifying each T/R bladein accordance with FAA-approved data by installing a titanium rivet at the outboard end and painting the letter "T'' on the root-end of the T/R blade to indicate the modification has been accomplished is considered a terminating action for the requirements of this AD.

(c) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Contact the Manager, Los Angeles Aircraft Certification Office, FAA, ATTN: John Cecil, Aviation Safety Engineer, 3960 Paramount Blvd., Lakewood, California 90712-4137, telephone (562) 627-5228, fax (562) 627-5210, for information about previously approved alternative methods of compliance.

(d) Special flight permits will not be issued.

(e) The inspection shall be done in accordance with the specified portions of Helicopter Technology Company, LLC (HTC) Mandatory Service Bulletin Notice No. 3100-4R4, dated May 10, 2006. The Director of the Federal Register approved this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from HTC, 12902 South Broadway, Los Angeles, California, 90061, telephone (310) 523-2750, fax (310) 523-2745, or on the Internet at http://www.helicoptertech.com. Copies may be inspected at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_ regulations/ibr_locations.html.

(f) This amendment becomes effective on September 3, 2008.

A proposal to amend 14 CFR part 39 to include an AD for the specified model helicopters was published in the Federal Register on March 13, 2008 (73 FR 13515). That action proposed to require, within 25 hours time-in-service (TIS), and thereafter at intervals not to exceed 25 hours TIS, tap inspections of the upper and lower surfaces of each T/R blade abrasion strip using a coin (United States 25-cent piece or equivalent), or a small brass, mild steel, or aluminum hammer, to detect bonding voids that exceed 0.2 square inch in size with a minimum of 1.0 inch between voids, at least 75 percent of the bonded area of the abrasion strip being free from voids, and no voids at the edge of the abrasion strip. Also proposed was a terminating action of modifying each T/R blade in accordance with FAA- approved data by installing a titanium rivet in the tip of the outboard end of each T/R blade and painting a "T'' on the root-end of the T/R blade.
We have reviewed thefollowing service information:
HTC Mandatory Service Bulletin Notice No. 3100-4R4, dated May 10, 2006, which describes procedures for periodic inspection of the abrasion strip-to-skin bond integrity on each T/R blade, and modifying each T/R blade by installing a titanium rivet, P/N 500P3124-13, in the tip of the T/R blade, and painting a "T'' on the root-end of the T/R blade in accordance with applicable engineering drawings or standard repair instructions; and
MD Helicopters Service Bulletin SB369D-203R1, SB369E- 097R1, SB369F-082R1, and SB369H-246R1, dated January 23, 2006, which describes procedures for periodic inspections of the T/R abrasion strip-to-skin bond integrity and modification of the T/R blade by HTC to install a titanium rivet in the tip of the T/R blade.
Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposal or the FAA's determination of the cost to the public. The FAA hasdetermined that air safety and the public interest require the adoption of the rule as proposed.
The FAA estimates that this AD will affect 718 helicopters of U.S. registry.
If operators conduct the repetitive inspections required by this AD instead of modifying their T/R blades by installing a titanium rivet, the estimated costs per year is $229,760 per year, assuming:
24 inspections per year per helicopter (600 hours TIS per 25 hour TIS inspection),
Labor of 5 minutes per T/R blade (10 minutes (\1/6\ hour) per helicopter), and
An average labor rate of $80 per work hour.
If operators elect to implement the terminating action by installing a titanium rivet in each T/R blade, the estimated total cost is $244,120, assuming:
The cost of removing, reinstalling, and balancing the 2-T/ R blade set for the entire fleet is $114,880, assuming that it takes 2 work hours per helicopter to perform these actions at an average labor rate of $80 per work hour, and
The cost ofinstalling the rivet in each T/R blade in the fleet is $129,240, which includes the cost of $10 per rivet ($20 per helicopter), 1 work hour per T/R blade (2 work hours per helicopter) to install a rivet, at an average labor rate of $80 per work hour.

Regulatory Findings

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD 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.
For the reasons discussed above, I certify that the regulation:

1. Is not a "significant regulatory action'' under Executive Order 12866;
2. Is not a "significant rule'' under the 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.
We prepared an economic evaluation of the estimated costs to comply with this AD. See the AD docket to examine the economic evaluation.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, section 44701, "General requirements.'' Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: