06-4107. Airworthiness Directives; Eurocopter France Model AS-365N2, AS 365 N3, EC 155B, EC155B1, SA-365N, N1, and SA-366G1 Helicopters

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes to revise an existing airworthiness directive (AD) for Eurocopter France (Eurocopter) Model AS-365N2, AS 365 N3, EC 155B, EC155B1, SA-365N, N1, and SA-366G1 helicopters. That AD currently requires inspecting the main gearbox (MGB) base plate for a crack and replacing the MGB if a crack is found. This action would increase the time intervals for inspecting the MGB base plate. This action would also include minor editorial changes throughout the AD. This proposal is prompted by crack growth tests that indicate that the inspection intervals can be increased without affecting safety. The actions specified by the proposed AD are intended to detect a crack in an MGB base plate and prevent failure of one of the MGB attachment points to the frame, which could result in severe vibration and subsequent loss of control of the helicopter.

DATES:

Comments must be received by July 3, 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 American Eurocopter Corporation, 2701 Forum Drive, Grand Prairie, Texas 75053-4005, telephone [phone], fax [phone].

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:

Ed Cuevas, Aviation Safety Engineer, FAA, Rotorcraft Directorate, Safety Management Group, Fort Worth, Texas 76193-0111, 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-2004-18850, Directorate Identifier 2004-SW-19-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 August 4, 2004, we issued AD 2004-16-15, Amendment 39-13771 (69 FR 51358, August 19, 2004), to require visually inspecting the MGB for a crack in the MGB base plate, part number (P/N) 366A32-1062-03 or P/N 366A32-1062-06, close to the attachment hole using a 10x or higher magnifying glass. Stripping paint from the inspection area is also required, but only before the initial inspection. That action was prompted by the discovery of a crack in the MGB base plate of an MGB installed in a Model AS-365 N2 helicopter. The crack was located very close to the attachment points of one of the laminated pads, and it propagated to the inside of the MGB base plate and then continued into the MGB casing. That condition, if not detected, could result in failure of one of the MGB attachment points to the frame, which could result in severe vibration and subsequent loss of control of the helicopter.

When we issued AD 2004-16-15, the cause of crack in the MGB base plate was still under investigation; therefore, we considered the previously issued AD to be interim action until the cause of the crack could be determined. The cause of the crack is still under investigation. However, since issuing AD 2004-16-15, crack growth tests have shown that the inspection intervals can be increased without affecting safety. We made this determination after Eurocopter conducted crack growth testing in laboratory bench tests. A cracked base plate was loaded with an alternating torque to simulate flight loading and cycles. Crack propagation speed was measured and assessed over a longer duration than the initial inspection interval and this resulted in extending the inspection intervals. The first inspection interval was determined using crack striations, which was a quick and conservative method used to ensure airworthiness and allow for timely issuance of service information by the manufacturer. Based on this additional information, we are proposing to increase the time intervals between each required inspection, however, the actions specified by this proposed AD are still considered to be interim. We are also proposing to include minor editorial changes in the AD.

The Direction Générale de L'Aviation Civile (DGAC), the airworthiness authority for France, notified the FAA that an unsafe condition may exist on Eurocopter Model SA 365N, N1, SA 366 G1, AS 365 N2, N3, EC 155 B, and B1 helicopters, all serial numbers. The DGAC advises that a crack was detected in the MGB base plate of an AS 365 N2 helicopter. The crack was detected in the MGB base plate web, very close to the attachment of one of the laminated pads, and runs to the inside of the MGB base plate and then on the MGB casing. In time, the growth of the crack may lead to the loss of the transfer of rotor torque to the rotorcraft structure.

Eurocopter has issued Alert Service Bulletin (ASB) No. 05.00.45 for Model AS365 N, N1, N2, and N3 helicopters; ASB No. 05.29 for Model SA366 G1 helicopters; and ASB No. 05A005 for Model EC155 B and B1 helicopters. All of the ASBs are dated November 8, 2004 and supersede previously issued Eurocopter Alert Telex No. 05.00.45, No. 05.29, and No. 05A005, all dated February 5, 2004. The ASBs specify the same actions as the alert telexes—visually inspecting the MGB base plate for the absence of cracks, using a 10x magnifying glass to facilitate the crack inspection, and, if in doubt about the existence of a crack, inspecting for a crack using a dye-penetrant crack detection inspection. However, for the Eurocopter Model AS365 N, N1, N2, N3, and SA366 G1 helicopters, the 15-flying hour check for the MGB base plate that is specified in the alert telexes is replaced with check intervals not to exceed 55 flying hours. For the EC155 B and B1 helicopters, the check after the last flight of each day and without exceeding a 9-flying hour check interval is replaced with check intervals not to exceed 15 flying hours.

The DGAC classified ASB Nos. 05.00.45, 05.29, and 05A005 as mandatory and issued AD No. F-2004-023 R1, dated November 24, 2004, to ensure the continued airworthiness of these helicopters in France.

These helicopter models are manufactured in France and are type certificated for operation in the United States under the provisions of 14 CFR 21.29 and the applicable bilateral agreement. Pursuant to the applicable bilateral agreement, the DGAC has kept the FAA informed of the situation described above. We have examined the findings of the DGAC, reviewed all available information, and determined that AD action is necessary for products of these type designs that are certificated for operation in the United States.

This previously described unsafe condition is likely to exist or develop on other helicopters of the same type designs. Therefore, the proposed AD would revise AD 2004-16-15 to require initial and repetitive inspections of the MGB base plate for cracking at various short time intervals. The time intervals for doing the inspections would be increased from what is required in the existing AD and are dependant on the helicopter model and the number of cycles on the MGB and whether the MGB has ever been overhauled or repaired.

We estimate that this proposed AD would affect 142 helicopters of U.S. registry. The initial inspection would take about 0.5 work hour and each recurring inspection would take about 0.25 work hour. Replacing the MGB, if necessary, would take about 4 work hours. The average labor rate would be $65 per work hour. It would cost approximately $25,000 to repair a cracked MGB base plate. Based on these figures, the total estimated cost impact of the AD on U.S. operators would be $56,249, assuming that each of the 135 Model AS 365 and SA 366 helicopters are inspected 11 times (the initial inspection plus 10 recurring inspections) and each of the 7 Model EC 155 helicopters are inspected 40 times (the initial inspection plus 39 recurring inspections), and one cracked MGB base plate is found requiring the repair and replacement of one MGB. This estimate also assumes that a replacement MGB would not need to be purchased while a previously-installed MGB is being repaired.

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 39-13771 (69 FR 51358, August 19, 2004), and by adding a new airworthiness directive (AD), to read as follows:

Eurocopter France: Docket No. FAA-2004-18850; Directorate Identifier 2004-SW-19-AD. Revises AD 2004-16-15, Amendment 39-13771.

Applicability: Model AS-365N2, AS 365 N3, EC 155B, EC155B1, SA-365N, N1, and SA-366G1 helicopters with a main gearbox (MGB) base plate, part number (P/N) 366A32-1062-03 or P/N 366A32-1062-06, installed, certificated in any category.

Compliance: Required as indicated in the following compliance table and before installing a replacement main gearbox (MGB).

Compliance Table

For model . . .	If . . .	Or if . . .	Or if . . .
(1) SA-365N, N1 and SA-366G1 helicopters	An MGB is installed that has less than 9,900 cycles and has never been overhauled or repaired, on or before accumulating 9,900 cycles, unless accomplished previously, and thereafter, at intervals not to exceed 55 hours time-in-service (TIS)	An MGB is installed that has 9,900 or more cycles and has never been overhauled or repaired, before further flight, unless accomplished previously, and thereafter, at intervals not to exceed 55 hours TIS	An MGB is installed that is overhauled or repaired, before further flight, unless accomplished previously, and thereafter, at intervals not to exceed 55 hours TIS.
(2) AS-365N2 and AS 365 N3 helicopters	An MGB is installed that has less than 7,300 cycles and has never been overhauled or repaired, on or before accumulating 7,300 cycles, unless accomplished previously, and thereafter, at intervals not to exceed 55 hours TIS	An MGB is installed that has 7,300 or more cycles and has never been overhauled or repaired, before further flight, and thereafter, at intervals not to exceed 55 hours TIS	An MGB is installed that has been overhauled or repaired, before further flight, and thereafter, at intervals not to exceed 55 hours TIS.
(3) EC 155 B and EC155B1 helicopters	An MGB base plate is installed that has less than 2,600 cycles, no later than 2,600 cycles, unless accomplished previously, and thereafter, at intervals not to exceed 15 hours TIS	An MGB base plate is installed that has 2,600 or more cycles, unless accomplished previously, before further flight, and thereafter, at intervals not to exceed 15 hours TIS
One cycle equates to one helicopter landing in which a landing gear touches the ground.

To detect a crack in the MGB base plate and prevent failure of a MGB attachment point to the frame, which could result in severe vibration and subsequent loss of control of the helicopter, accomplish the following:

(a) Before the initial inspection at the time indicated in the compliance table of this AD, strip the paint from area “D” on both sides (“B” and “C”) of the MGB base plate as depicted in Figure 1 of this AD.

(b) At the times indicated in the compliance table, inspect area “D” of the MGB base plate for a crack using a 10x or higher magnifying glass. Area “D” to be inspected is depicted in Figure 1 of this AD.

Note 1:

Eurocopter France Alert Service Bulletin (ASB) No. 05.00.45 for Model AS365 N, N1, N2, and N3 helicopters, ASB No. 05.29 for Model SA366 G1 helicopters, and ASB No. 05A005 for Model EC155 B and B1 helicopters, pertain to the subject of this AD. All three ASBs are dated November 8, 2004.

(c) If a crack is found in a MGB base plate, remove and replace the MGB with an airworthy MGB before further flight.

(d) 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, Safety Management Group, Rotorcraft Directorate, FAA, ATTN: Ed Cuevas, Fort Worth, Texas 76193-0111, telephone [phone], fax [phone], for information about previously approved alternative methods of compliance.

Note 2:

The subject of this AD is addressed in Direction Générale de L'Aviation Civile (France) AD F-2004-023 R1, dated November 24, 2004.

Issued in Fort Worth, Texas, on April 21, 2006.

Mark R. Schilling,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.