**[4910 -**  **13 -**  **P ]** 

**DEPARTMENT OF TRANSPORTATION Federal Aviation Administration**  **14 CFR Part 39 [Docket No.**  **FAA -**  **2010 -**  **XXXX ; Directorate Identifier**  **2010 -**  **SW -**  **031 -** **AD ]**  **RIN 2120 -** **AA64 Airworthiness Directives;**  **MD Helicopters, Inc. Helicopters**  **AGENCY:** Federal Aviation Administration, DOT. **ACTION:** Notice of proposed rulemaking (NPRM) . **SUMMARY:** We propose to adopt a new airworthiness directive (AD) for the MD Helicopters, Inc. (MDHI) Model MD900 helicopters with certain main rotor blade retention bolts (bolts) installed . This proposed AD would require a dail y check of the position of each bolt and for a gap, and a repetitive inspection of each bolt for a gap. The proposed AD would also require, if necessary , removin g and inspecting the bolt for a crack and replacing any cracked bolt with an airworthy bolt. Thi s proposed AD is prompted by

multiple reports of in - service bolt failures. The proposed actions are intended to prevent failure of a bolt, which could lead to loss of main rotor blade (MRB) structural integrity, and subsequent loss of control of the helicopter . **DATES:** We must receive comments on this proposed AD b y [ INSERT DATE 60 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGI STER]. **ADDRESSES:** You may s end c omments by any of the following methods:

 Federal eRulemaking Docket : Go to http://www.regulations.gov . Follow the online instructions for sending your comments electronicall y.2  Fax : 202 - 493 - 2251.

 Mail : Send comments to the U.S. Department of Transportation, Docket Operations, M - 30, West Building Ground Floor, Room W12 - 140, 1200 New Jersey Avenue SE, Washington, DC 20590 - 0001.

 Hand Delivery : Deliver to the “Mail” address between 9 a.m. and 5 p.m., Monday through Friday , except Federal holiday s. **EXAMINING THE AD DOCKET:** You may examine the AD docket on the Internet at http://www.regulations.gov or in person at the Docket Operations Office between 9 a.m. and 5 p.m., Monday

through Friday , except Feder al holiday s. The AD docket contains this proposed AD, the economic evaluation , any comments received, and other information. The street address for the Docket Operations Office (telephone 800 - 647 - 5527) is in the ADDRESSES section. Comments will be availabl e in the AD docket shortly

after receipt. For service information identified in this proposed AD, contact MD HI , Attn: Customer Support Division, 4555 E. McDowell Rd., Mail Stop M615, Mesa, AZ 85215 - 9734, telephone ( 800 ) 388 - 3378, fax ( 480 ) 346 - 6813, or at http://www.mdhelicopters.com . You may review copies of the referenced service information at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. **F OR FURTHER INFORMATION CONTACT:**  Roger Durbin, Aerospace Engineer, FAA, Los Angeles Aircraft Certification Office, Airframe Branch, ANM - 120L , 3960 Paramount Blvd., Lakewood, CA 90712, telephone (562) 627 - 5233, fax (562) 627 - 5210, email roger.durbin@faa.gov .3

**SUPPLEMENTARY INFORMATION: Comments Invited**  We invite you to participate in this rulemaking b y submitting written comments, data, or views. We also invite comments relating to the economic, environmental, energy , or federalism impacts that might result from adopting the proposals in this document. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. To ensure the docket does not contain duplicate comments, comm enters should send only one copy of written comments, or if comments are filed electronically , commenters should submit only one time. We will file in the docket all comments that we receive, as well as a report summarizing each substantive public contact with FAA personnel concerning this proposed rulemaking. Before acting on this proposal, we will consider all comments we receive on or before the closing date for comments. We will consider comments filed after the comment period has closed if it is possib le to do so without incurring expense or delay . We may

change this proposal in light of the comments we receive. **Discussion** We propose to adopt a new AD for MDHI Model MD900 helicopters with certain bolts installed . This proposed AD is pro mpted by multiple reports of in - service bolt failures , which could lead to loss of the MRB structural integrity and subsequent loss of control of the helicopter. Although these bolt failures have primaril y occurred in the United Kingdom, it is possible that the failures af fect MDHI Model 900 helicopters in the4

United States. This condition, if not detected , could lead to loss of MRB structural integrity and subsequent loss of control of the helicopter . **FAA’s Determination** We are proposing this AD because we evaluated all known relevant information and determined that an unsafe condition exists and is likely to exist or develop on other products of the same typ e design . **Related Service Information** We have reviewed MDHI Alert Service Bulletin SB900 - 116R1, dated April 9, 2010 (ASB SB900 - 116R1), which supersedes ASB SB900 - 116, dated February 24, 1010 (ASB SB900 - 116). ASB SB900 - 116 specifies a repetitive check of the blade retention bolts, part number (P/N) 900R3100001 - 103 and 900R3100001 - 105, for a gap, and, depending on the o utcome of the inspection, removing and inspecting the bolt for damage. The ASB also specifies a repetitive force check of each bolt, P/N 900R3100001 - 103, and a torque check of each bolt, P/N 900R3100001 - 105. Lastly, the ASB specifies a daily preflight chec k of each bolt to examine the position of the bolt and for a gap, and, i f any bolt has moved up or down or if there was no gap, removing and inspecting the bolt . Superseding ASB SB900 - 116R1 retains the same specifications as ASB SB90016, except that it revises the interval for the bolt force and torque checks from 4 - 6 flight - hours to 8 - 10 flight - hours. ASB SB90016R1 also revises the change of force or torque from not more than 10 percent to not more than ±10 percent. **Proposed AD Requirements** The proposed AD would require:5  Before the first flight of each day , visually checking the position of each bolt for up or down displacement and visually checking for a gap between the thrust washer and the retainer. If any bolt has moved up or down , or if there is no gap between the thrust washer and retainer, before further flight, a qualified mechanic must remove and inspect the bolt for a crack and replace any unairworthy bolt with an airworthy bolt. An owner/operator (pilot) may perform the visual check req uired by paragraph (e) of this proposed AD and must enter compliance with that paragraph into the helicopter maintenance records. In accordance with 14 CFR 43.9(a)(1) - (4) and 91.417(a)(2)(v), a pilot may perform this check because it involves only a visual check for the position of the bolt and a check for a gap between the thrust washer and retainer and can be performed equall y well by a pilot or mechanic.

 Within 300 hours TI S and thereafter at intervals not to exceed 300 hours TIS, inspecting each bolt for a gap between the thrust washer and the retainer. °I f there is a missing O - ring, installing any missing O - ring, P/N NAS617 - 10. °I f there is no gap , before further flight, remov ing and inspecting the bolt for a crack and replacing any unairworth y bolt w ith an airworthy bolt. °I f there is a gap, measuring the gap in two locations, 180 degrees apart, with a feeler gage. If the gap is more than 0.100 inch (2.54 mm), before further flight, removing and inspecting the bolt for a crack and replacing any unairworth y bolt with an airworthy bolt. **Differences between this Proposed AD and the Service Information**6 This proposed AD uses the term “inspect” when describing the action of inspecting a bolt for a crack and inspecting for a gap between the thrust washer a nd the retainer. The ASB uses the term “check.” **Costs of Compliance** We estimate that this proposed AD would affect 29 helicopters in the U.S. registry . We estimate that operators may incur the following costs in order to comply with this AD: It would take .5 work hour to do a gap inspection of each bolt, assuming 2 inspections per year, and 2 work hours to check for up or down displacement of each bolt, assuming 365 checks per year, at $85 per hour. The required parts would be $800. **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 mo re 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 conditio n that is likely to exist or develop on products identified in this rulemaking action.7

**Regulatory Findings** We determined that this proposed AD would not have federalism implications under Executive Order 13132. 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, Icertify this proposed regulation: 1. Is not a “significant regulatory action” under Executive Order 12866; 2. I s not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 3. Will not affect intrastate aviation in Alaska to the extent that it justifies making a regulatory

distinction; and 4. 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 proposed AD and placed it in the AD docket. **List of Subjects in 14 CFR Part 39** Air transportation, Aircraft, Aviation safety, Incorporation by Reference , Safety. **The Proposed Amendment** Accordingl y, under the authority de legated to me by

the Administrator, the FAA proposes to amend 14 CFR part 39 as follows: **PART 39 -**  **AIRWORTHINESS DIRECTIVES** 1. The authority citation for part 39 continues to read as follows:8 Authority : 49 U.S.C. 106(g), 40113, 44701. **§ 39.13 [Amended]**  2. The FAA amends § 39.13 by adding the following new Airworthiness Directive (AD): **MD HELICOPTERS, INC. (MDHI) :**  Docket No. FAA - 2011 - XXXXX ; Directorate Id entifier 2010 - SW - 031 - AD . **(a) Applicability**  **.** This AD applies to Model MD 900 helicopters w ith a main rotor blade retention bolt (bolt), part number (P/N) 900R3100001 - 103 or 900R3100001 - 105 , installed ; certificated in any category. **(b) Unsafe Condition**  **.** This AD defines the unsafe condition as bolt failure. This condition could result in loss of main rotor blade (MRB) structural integrity and subsequent loss of control of the helicopter. **(c) Compliance.**  You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time. **(d) Required Actions.**  (1) Before the first flight of each day : (i) Visually

check each bolt for failure. Failure of a bolt may be indicated by movement of the bolt out of the bo lt hole or inconsistent extension of the bolt above or below the other bolts being inspected (failed bolt is migrating out of the bolt hole).9 (ii) Visually

check for a gap between the thrust washer and the retainer. The thrust washer is depicted as item 2 and the retainer is depicted as item 8 in Figure 1 to paragraph (d). (iii) The actions required by paragraphs (d)(1)(i) and (d)(1)(ii) may be performed by the owner/operator (pilot) holding at least a private pilot certificate and must be entered into the aircraft maintenance records showing compliance with this AD in accordance with 14 CFR §§ 43. 9(a)(1) - (4) and 14 CFR § 91.417(a)(2)(v). The record must be maintained as required by 14 CFR §§ 91.417, 121.380, or 135.439. (iv) If there is any indication of bolt failure, or if there is no gap between the thrust washer and retainer, before further flight, remove and inspect the bolt for a crack. Replace any cracked bolt with an airworthy bolt. (2) Within 300 hours time - in - service (TI S), and thereafter at intervals not to exceed 300 hours TIS, inspect each bolt for a gap between the thrust washer and the retainer, P/N 900R2100009 - 101 or - 103 , as depicted in Figure 1 to paragraph (d) of this AD .1011 ( i ) Determine whether an O - ring, P/N NAS617 - 10 , is in stalled. Install any missing O - ring. (ii ) If there is no gap between the thrust washer and retainer, before further flight, remove and inspect the bolt for a crack. Replace any cracked bolt with an airworthy bolt. (iii) If there is a gap between the thrust washer and retainer, measure the gap in two locations, 180 degrees apart, with a feeler gage . I f the gap is more than 0.100 inch (2.54 mm) at either location, before further flight, remove and inspect the bolt for a crack. Replace any cracked bo lt with an airworthy bolt. **(e) Alternative Methods of Compliance**  ( 1 ) The Manager, Los Angeles Aircraft Certification Office , Airframe Branch (ANM - 120L), FAA, may approve AMOCs for this AD . Send your request to Roger Durbin, Aerospace Engineer, FAA, Los Angeles Aircraft Certification Office, Airframe Branch, ANM - 120L , 3960 Paramount Blvd., L akewood, CA 90712, telephone (562) 627 - 5233, fax (562) 627 - 5210, email roger.durbin@faa.gov . (2) For operations conducted under a 14 CFR part 119 operating certificate or under 14 CFR part 91, subpart K, we suggest that you notify your principal inspector or lacking a principal inspector, the manager of the local flight standards district office o r certificate holding district office before operating any aircraft compl yi ng with this AD through an AMOC. **(f) Additional Information**  **.** MDHI Alert Service Bulletin SB900 - 116R1, dated April 9, 2010, which supersedes ASB SB900 - 116, dated February 24, 1010 , neither of which is incorporated by reference, contains additional information about the subject of this AD. For service12

information identified in this AD, contact MDHI, Attn: Customer Support Division, 4555 E. McDowell Rd., Mail Stop M615, Mesa, AZ 8521 5 - 9734, telephone (800) 388 - 3378, fax (480) 346 - 6813, or at http://www.mdhelicopters.com . You may review copies of the service information at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas. **( g** **) Subject.**  Joint Aircraft S ys tem Component: 6210 : Main ro tor blade r etention b olts. Issued in Fort Worth, Texas, on