AD 97-13-09

Effective July 10, 1997.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of July 10, 1997.

Comments for inclusion in the rules docket must be received on or before August 25, 1997.

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Assistant Chief Counsel, Attention: Rules Docket No. 96-SW-35-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137.

The service information referenced in this AD may be obtained from McDonnell Douglas Helicopter Systems, Technical Publications, Bldg. 530/B11, 5000 E. McDowell Road, Mesa, Arizona 85205-9797. This information may be examined at the FAA, Office of the Assistant Chief Counsel, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Mr. Greg DiLibero, Aerospace Engineer, Airframe Branch, Los Angeles Aircraft Certification Office, FAA, 3960 Paramount Boulevard, Lakewood, California 90712, telephone (562) 627-5231, fax (562) 627-5210.

This amendment adopts a new AD that is applicable to MDHS Model MD-900 helicopters. For Model MD-900 helicopters with serial numbers (S/N) 0002 through 0012, this action requires applying serial numbers to the mid-forward truss assembly, part number (P/N) 900F2401200-102, and the forward and aft deck-fitting assemblies, P/N 900F2401500-103 and P/N 900F2401600-103. For Model MD-900 helicopters with S/N 0002 through 0048, this action requires applying S/N's to the VSCS bellcrank assemblies, part number (P/N) 900F2341712-101 or P/N 900FP341712-103, and the mid-aft truss strut assembly, P/N 900F2401300-103. For all Model MD-900 helicopters, this action reduces the life limits for the non-rotating swashplate assembly, P/N 900C2010192-105, -107, -109, or -111, from 8,300 hours time-in-service (TIS) to 554 hours TIS; the collective drive link assembly, P/N 900C2010207-101, from 3,900 hours TIS to 1,480 hours TIS; the self-aligning, spherical/slider main rotor bearing, P/N 900C3010042-103, from 2,100 hours TIS to 480 hours TIS; and the VSCS bellcrank assembly, P/N 900FP341712-103, and bellcrank arm, P/N 900F2341713-101, (used in the VSCS bellcrank assembly, P/N 900F2341712-101) from no life limit to 2,700 hours TIS. This amendment is prompted by additional manufacturer's analysis which indicates a need for the reduction of the life limit on several parts and the addition of non-serialized parts to the life-limited parts list. The actions specified in this AD are intended to establish a life limit for various parts and reduce the current life limit on other parts.

The FAA has reviewed McDonnell Douglas Helicopter Systems Service Bulletin No. SB900-039, Revision 2, dated March 12, 1997, which describes procedures for applying the serial numbers to the life-limited parts.

Since an unsafe condition has been identified that is likely to exist or develop on other MDHS Model MD-900 helicopters of the same type design, this AD is being issued to establish a life limit for various parts and reduce the current life limit on other parts. This AD requires applying specified serial numbers to the left and right VSCS bellcrank assemblies, P/N 900F2341712-101 or P/N 900FP341712-103; to the mid-forward and mid-aft truss strut assemblies, P/N 900F2401200-102 and P/N 900F2401300-103; and to the forward and aft deck-fitting assemblies, P/N 900F2401500-103 and P/N 900F2401600-103. This AD also reduces the life limits for the non-rotating swashplate assembly, P/N 900C2010192-105, -107, -109, or -111, from 8,300 hours TIS to 554 hours TIS; the collective drive link assembly, P/N 900C2010207-101, from 3,900 hours TIS to 1,480 hours TIS; the self-aligning, spherical/slider main rotor bearing, P/N 900C3010042-103, from 2,100 hours TIS to 480 hours TIS; and the VSCS bellcrank assembly, P/N 900FP341712-103, and the bellcrank arm, P/N 900F2341713-101, (used in the VSCS bellcrank assembly, P/N 900F2341712-101) from no life limit to 2,700 hours TIS. The serial numbers for the VSCS bellcrank assemblies, the mid-forward and mid-aft truss assemblies, and the forward and aft deck-fitting assemblies are specified in and are required to be accomplished in accordance with the service bulletin described previously. The serial numbers specified in the service bulletin shall be applied adjacent to the existing P/N's. Some Model MD-900 helicopters that are currently in service are equipped with helicopter control system parts that are approaching the new, lower life limits. Failure of any of these parts could result in loss of control of the helicopter. Due to the criticality of the components of the helicopter control system, this AD is being issued in the form of an immediately-adopted final rule with request for comments.

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

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. 96-SW-35-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.

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

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:

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.