E6-7092. Airworthiness Directives; MD Helicopters, Inc. Model MD900 Helicopters

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes superseding an existing airworthiness directive (AD) for MD Helicopters, Inc. (MDHI) Model MD900 helicopters. That AD currently requires reducing the life limit of certain Notar fan system tension-torsion (TT) straps. That AD also requires, at a specified time interval, removing each affected TT strap from the helicopter, doing a visual and X-ray inspection, and replacing any unairworthy part before further flight. This AD would require the same actions as the existing AD, but would also require revising the life limit on the component history card or equivalent record, doing repetitive visual and X-ray inspections, and would remove reporting requirements. This proposal is prompted by two in-flight TT strap failures. The actions specified by the proposed AD are intended to prevent failure of a TT strap, loss of directional control, and subsequent loss of control of the helicopter.

DATES:

Comments must be received on or before July 10, 2006.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD:

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically;
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically;
• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590;
• Fax: [phone]; or
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

You may get the service information identified in this proposed AD from MD Helicopters Inc., Attn: Customer Support Division, 4555 E. McDowell Rd., Mail Stop M615, Mesa, Arizona 85215-9734, telephone [phone], fax [phone], or on the Web at http://www.mdhelicopters.com.

You may examine the comments to this proposed AD in the AD docket on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT:

Roger Durbin, Aviation Safety Engineer, FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone [phone], fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any written data, views, or arguments regarding this proposed AD. Send your comments to the address listed under the caption ADDRESSES. Include the docket number “FAA-2006-24631, Directorate Identifier 2005-SW-01-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed rulemaking. Using the search function of our docket Web site, you can find and read the comments to any of our dockets, including the name of the individual who sent or signed the comment. You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may visit http://dms.dot.gov.

Examining the Docket

You may examine the docket that contains the proposed AD, any comments, and other information in person at the Docket Management System (DMS) Docket Office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone [phone]) is located at the plaza level of the Department of Transportation Nassif Building in Room PL-401 at 400 Seventh Street, SW., Washington, DC. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

On November 10, 2004, we issued a Final Rule; Request for Comments. That AD, 2004-23-15, Amendment 39-13870 (69 FR 67805, November 22, 2004), requires reducing the life limit of certain TT straps. At a specified time interval, that AD also requires removing each affected TT strap from the helicopter, doing a visual and X-ray inspection, and replacing any unairworthy part before further flight. Reporting the discovery of any unairworthy TT strap is also required. That action was prompted by two in-flight TT strap failures. The requirements of that AD are intended to prevent failure of a TT strap resulting in loss of directional control and subsequent loss of control of the helicopter.

At the time we issued AD 2004-23-15, the cause of the failures was not known, and that AD was considered interim action. These proposals also are interim actions because the cause of the failures is still unknown and the investigation is ongoing. We will consider further rulemaking once our investigation is complete.

Before issuing that AD, we reviewed MD Helicopters Service Bulletin SB-900-095, dated November 3, 2004. The service bulletin advises of the reduction of the TT strap life limit and describes procedures for performing an inspection of each TT strap for nicks, cuts, cracks, or wear. Procedures for a Level II or higher X-Ray technician to do and interpret an X-ray inspection of each TT strap for progressive fiber fractures are also included in the service bulletin.

Since issuing AD 2004-23-15, we received several comments from the manufacturer and have given them due consideration. The following table lists requested changes and comments and our responses:

Requested change/comment	FAA response
1. Change the comments due date from January 21, 2004, to January 21, 2005	We agree with this change and published a correction for this typographical error in the Federal Register on December 23, 2004 (69 FR 76979).
2. Correct the manufacturer's address and the fax number	We have corrected the address and fax number. This proposed AD contains the correct address and fax number.
3. The commenter suggests we clarify when the initial visual and X-ray inspections should begin. For example, instead of stating “within 10 hours TIS for any TT strap that has accumulated 1190 or more hours TIS,” write it as: “For any TT strap that has accumulated 1190 or more hours TIS, within 10 hours TIS * * *” The commenter suggests this change be made in the preamble as well as paragraphs (b) and (c) of the AD language	The suggestion of first describing the part affected followed by the compliance time is an acceptable method of organizing an AD. The FAA has used that method. However, we believe that after determining if the AD applies to their product, operators generally want to know when they have to comply with the AD. Therefore, in general, we attempt to place the compliance times at the beginning of a paragraph. Each organizational approach has its merits. However, we have chosen to continue to use the same organization in this proposal as we used in AD 2004-23-15.
4. The commenter suggests that we use the word “complete” instead of “do” or “doing” in the AD where we state the compliance requirements	Although these words have the same meaning, under plain-language concepts, the shorter, simpler word is preferred. Therefore, we are continuing to use “do” instead of “accomplish” or “complete,”
5. The commenter suggests that we add the following language to the preamble discussion of the AD as well as add it as a note to the AD language: “Although not part of this AD, the FAA has required a 300 repetitive hour visual and x-ray inspection of the straps after the initial inspection required by this AD. This requirement can be found as a note for each of the TT straps Part Numbers listed in the FAA Approved Airworthiness Limitations Section of the Maintenance Manual.”	We agree that the 300-hour TIS repetitive inspection needs to be mandated by AD. We issued AD 2004-23-15 as a Final Rule; Request for comments (an immediately adopted rule (IAR)) without prior public notice and comment because the inspections mandated by that AD were required within a very short time period. An IAR is an exception to the normal prior public notice and comment procedures of the Administrative Procedures Act (5 U.S.C. 553) and is based on a good-cause finding of impracticable, unnecessary, or contrary to the public interest. Likewise, 14 CFR part 11 and DOT Regulatory Policies and Procedures guide our rulemaking.
	Based on these rulemaking constraints, we could not justify inserting a long-term requirement, such as a 300-hour TIS inspection, into an IAR. However, we should have discussed our plan to implement the long-term repetitive requirements in the preamble discussions of the IAR.
	We plan to add the recurring 300-hour TIS inspection after issuing an NPRM and seeking public comments. We are doing that with this proposal.
	As to the comment that we add language to the AD in a note requiring a repetitive 300-hour TIS visual and X-ray inspection, it is inappropriate to place a mandatory requirement in an AD note. Notes in ADs are appropriate for providing helpful information, not required actions, to AD users. Thus far, we have not required a repetitive 300-hour TIS inspection of these affected TT strap part numbers.
	As to the comment that this requirement can be found as a note for each appropriate part number listed in the Limitation section of the maintenance manual, changes to the Airworthiness Limitations Section of the Instructions for Continued Airworthiness or Maintenance Manuals, even if FAA-approved, require compliance only if implemented through an AD. This action proposes to require the repetitive 300-hour TIS inspection sought by the commenter.
6. The commenter suggests the following editorial changes to the following sentence from paragraph (g) of the existing AD:	We do not agree that any editorial changes are necessary.
“This AD revises the Airworthiness Limitations section of the maintenance * * *” to “This AD revises the Airworthiness Limitations Section (ALS) of the maintenance * * *”
7. The commenter suggests that the new life limits be recorded on the Assembly Component Historical Record (CSP-RLB-L16 form).	We agree that the new life limit should be recorded and propose that change.
8. The commenter requests that the existing AD be superseded as soon as possible, but no later than February 7, 2005 “due to the critical nature of the recommended AD changes” and to ensure that operators do not overlook the 300-hour repetitive inspection	We agree that the repetitive inspection is important. The comment period for AD 2004-23-15 that we are proposing to supersede in this NPRM closed January 21, 2005. Thus, the February 7, 2005, compliance date requested by the commenter was unrealistically short and has already past. Since the comment period closed, the FAA has been processing this NPRM that proposes requiring an additional 300-hour TIS inspection to the other requirements currently in AD 2004-23-15.

We have also received several reports from operators as required by AD 2004-23-13. We included this reporting requirement to obtain sufficient field data that would allow us to verify that the mandated inspection interval would be adequate to manage the immediate short-term safety concern. Since issuing the AD, we have reviewed a sufficient number of reports to determine that the current interim inspection actions are adequate to ensure safety. Accordingly, we are proposing the remove the reporting requirements. However, this action is interim until the investigation is complete and final terminating action can be generated.

The previously described unsafe condition is likely to exist or develop on other helicopters of the same type design. Therefore, the proposed AD would supersede AD 2004-23-15 and would require the following for MDHI Model MD900 helicopters with a TT strap, part number (P/N) 900R3442009-103, 900R6442009-103, 900R3442009-101, or 500N5311-5, installed:

• Before further flight, unless accomplished previously, for TT strap, P/N 900R3442009-103 and 900R6442009-103, reducing the life limit from 3,034 to 2,500 hours TIS and revising the life limit on the component history card or equivalent record;
• Within 10 hours TIS, unless accomplished previously, and then at intervals not to exceed 300 hours TIS, for any TT strap that has accumulated 1,190 or more hours TIS, doing a visual and X-ray inspection of each TT strap and replacing any unairworthy TT strap before further flight; and
• Before the TT strap accumulates 1,200 hours TIS, and then at intervals not to exceed 300 hours TIS, for any TT strap with less than 1,190 hours TIS, doing a visual and X-ray inspection of each strap and replacing any unairworthy TT strap before further flight.

The inspections would have to be accomplished by following portions of the service information previously described.

We estimate that this proposed AD would affect 31 helicopters of U.S. registry. It would take about 7 work hours for each visual inspection and replacement at an average labor rate of $65 per work hour. Because you must remove the TT strap to inspect it, there is no additional labor cost for replacing the TT strap. It would also cost $100 for each X-ray inspection. Required parts would cost about $757 to replace each strap. Based on these figures, we estimate the total cost impact of the proposed AD on U.S. operators to be $168,950 in the first year (assuming a total of 5 TT straps are replaced per helicopter and 3 visual inspections and 3 X-ray inspections are conducted the first year for each helicopter).

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. Additionally, this proposed AD would 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 proposed 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 a draft economic evaluation of the estimated costs to comply with this proposed AD. See the DMS to examine the draft 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
• 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:

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 removing Amendment 39-13870 (69 FR 67805, November 22, 2004), and by adding a new airworthiness directive (AD), to read as follows:

MD Helicopters, Inc.: Docket No. FAA-2006-24631; Directorate Identifier 2005-SW-01. Supersedes AD 2004-23-15, Amendment 39-13870, Docket No. FAA-2004-19613, Directorate Identifier 2004-SW-38-AD.

Applicability: Model MD900 helicopters, with a Notar fan system that has a tension-torsion (TT) strap, part number (P/N) 900R3442009-103, 900R6442009-103, 900R3442009-101, or 500N5311-5, installed, certificated in any category.

Compliance: Required as indicated.

To prevent failure of a TT strap in the Notar fan system, loss of directional control, and subsequent loss of control of the helicopter, accomplish the following:

(a) Before further flight, unless accomplished previously, for TT Straps, P/N 900R3442009-103 and 900R6442009-103, reduce the life limit from 3,034 to 2,500 hours time-in-service (TIS) and revise the life limit on the component history card or equivalent record to reflect this reduced retirement life.

(b) Within 10 hours TIS, unless accomplished previously, for any TT strap that has accumulated 1,190 or more hours TIS, and then at intervals not to exceed 300 hours TIS, remove the TT strap from the helicopter and do a visual and an X-ray inspection in accordance with the Inspection Instructions, paragraph 2.B.(1). through (5)., and Figures 1 and 2 of MD Helicopters Service Bulletin SB900-095, dated November 3, 2004 (SB). Replace any unairworthy TT strap before further flight.

(c) Before the TT strap accumulates 1,200 hours TIS, for any TT strap with less than 1,190 hours TIS, and then at intervals not to exceed 300 hours TIS, remove the TT strap from the helicopter and do a visual and an X-ray inspection in accordance with the Inspection Instructions, paragraph 2.B.(1). through (5)., and Figures 1 and 2 of the SB. Replace any unairworthy TT strap before further flight.

(d) The X-ray inspection of the TT strap must be performed by a Level II or higher X-ray technician who is qualified under the guidelines established by MIL-STD- 410E, ATA Specification 105, AIA-NAS-410, or an FAA-accepted equivalent for qualification standards.

(e) This AD revises the Airworthiness Limitations section of the maintenance manual by reducing the life limit of the TT straps, P/N 900R3442009-103 and 900R6442009-103, from 3,034 hours TIS to 2,500 hours TIS. Additionally, this AD revises the Airworthiness Limitations section of the maintenance manual by adding repetitive inspection requirements at intervals not to exceed 300 hours TIS for TT straps, P/N 900R3442009-103, 900R6442009-103, 900R3442009-101, and 500N5311-5, that have 1,200 or more hours TIS until the TT strap reaches its retirement life.

(f) 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 Los Angeles Aircraft Certification, Transport Airplane Directorate, FAA, for information about previously approved alternative methods of compliance.

Issued in Fort Worth, Texas, on May 1, 2006.

Mark R. Schilling,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.