AD 94-15-08 ACTIVE

This amendment adopts a new airworthiness directive (AD) that is applicable to Robinson Helicopter Company Model R22 helicopters. This action requires an initial inspection and repetitive checks and visual inspections for corrosion and cracks on certain main rotor blades. This amendment is prompted by reports of chordwise cracks found in the main rotor blades. The actions specified in this AD are intended to prevent abnormal in-flight vibrations, failure of the main rotor blade, and subsequent loss of control of the helicopter.

Final rule; request for comments

94-15-08 ROBINSON HELICOPTER COMPANY: Amendment 39-8979. Docket Number 93-SW-16-AD.
Applicability: Model R22 helicopters, equipped with main rotor blades, part number (P/N) A016-2, with serial numbers (S/N) up to and including 7569 (including any suffixes), certificated in any category.
Compliance: Required as indicated, unless accomplished previously.
To prevent abnormal in-flight vibrations, failure of a main rotor blade (blade), and subsequent loss of control of the helicopter, accomplish the following:
(a) For blades that have less than 500 hours time-in-service (TIS) and have been installed on a helicopter for less than 1 year, visually inspect the blades' top and bottom skins for corrosion or cracks using a 5-power or higher magnifying glass in accordance with the applicable maintenance manual. Conduct this visual inspection upon or prior to the accumulation of 525 hours TIS or upon or prior to the blades being installed for 1 year, whichever occurs first.
(b) Forblades that have 500 or more hours TIS or have been installed on a helicopter for 1 year or more, within the next 25 hours TIS visually inspect the blades' top and bottom skins for corrosion or cracks using a 5-power or higher magnifying glass in accordance with the applicable maintenance manual.
(c) After the initial visual inspection required by paragraph (a) or (b), conduct the following inspections and checks:
(1) Visually inspect the blades' top and bottom skins for corrosion or cracks using a 5-power or higher magnifying glass at intervals not to exceed 100 hours TIS from the last inspection required by this AD.
(2) Visually check the blades' top and bottom skins for corrosion or cracks at intervals not to exceed 25 hours TIS from the last check or inspection required by this AD. The visual checks required by this AD may be performed by an owner/operator holding at least a private pilot certificate as authorized by section 43.7 of the Federal Aviation Regulations, and must be documented in the aircraft records showing compliance with this AD, in accordance with sections 43.11 and 91.417(a)(2)(v) of the Federal Aviation Regulations.
(d) Before further flight after the onset of abnormal vibrations of the main rotor system, visually inspect the blades' top and bottom skins for corrosion or cracks using a 5-power or higher magnifying glass.
(e) If a suspected crack is found in a blade during the inspections or checks required by this AD, conduct a dye penetrant or equivalent FAA-approved inspection for crack verification.
(f) If any crack is found in the blade skins, replace the blade with an airworthy blade before further flight.
(g) If any corrosion is found in the blade skins, repair or replace the blade with an airworthy blade in accordance with the provisions of the maintenance manual.
NOTE: Robinson Helicopter Company Service Bulletin #72, dated March 29, 1993, pertains to this AD.
(h) An alternative method of compliance or adjustmentof the compliance time that provides an acceptable level of safety may be used when approved by the Manager, Los Angeles Aircraft Certification Office, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Los Angeles Aircraft Certification Office.
NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from Los Angeles Aircraft Certification Office.
(i) Special flight permits to comply with this AD will not be issued.
(j) This amendment becomes effective on August 9, 1994.

This amendment adopts a new airworthiness directive that is applicable to Robinson Helicopter Company Model R22 helicopters equipped with main rotor blades, part number (P/N) A016-2, with serial numbers (S/N) up to and including 7569 (all suffixes), that have over 500 hours time-in-service (TIS) or more than 1 year TIS. The manufacturer reports finding two main rotor blades with cracks caused by corrosion on the main rotor blade skins. The cracks started at the trailing edge on both the upper and lower surfaces and extended several inches in the chordwise direction. The FAA has determined that corrosion or cracks in the main rotor blade skins create an unsafe condition. This condition, if not corrected, could result in abnormal in-flight vibrations, failure of the main rotor blade, and subsequent loss of control of the helicopter.

The FAA has reviewed Robinson Helicopter Company Service Bulletin (SB) #72, dated March 29, 1993, that describes procedures for a visual pilot check for corrosion or cracks in the skin of the main rotor blade, after the onset of any unusual vibrations, or within 25 hours TIS; and, thereafter at intervals of 4 months TIS. After reviewing the available data, the FAA has determined that repetitive visual inspections should be performed by a mechanic at intervals of 100 hours TIS, and the repetitive visual owner/operator (pilot) checks should be performed at intervals of 25 hours TIS.

Since an unsafe condition has been identified that is likely to exist or develop on other Robinson Helicopter Company Model R22 helicopters of the same type design, this AD is being issued to prevent abnormal in-flight vibrations, failure of the main rotor blade, and subsequent loss of control of the helicopter. This AD requires an initial visual inspection by a certificated mechanic, (1) for main rotor blades that have less than 500 hours TIS and have been installed for less than 1 year, upon or prior to the accumulation of 525 hours TIS or upon or prior to the main rotor blades having been installed for 1 year, whichever is earlier, or (2) for main rotor blades with 500 or more hours TIS or that have been installed for 1 year or more within the next 25 hours TIS. The inspection threshold is 1 year and 500 hours TIS. Thereafter, inspections for corrosion and cracks are required at intervals of not more than 100 hours TIS, or before further flight after the onset of abnormal vibrations. This AD also requires repetitive checks for corrosion and cracks in the main rotor blade at intervals not to exceed 25 hours TIS. These checks may be performed by an owner/operator holding at least a private pilot certificate as authorized by section 43.7 of the Federal Aviation Regulations but must be documented in the aircraft records showing compliance with this AD in accordance with sections 43.11 and 91.417(a)(2)(v) of the Federal Aviation Regulations. These checks do not require the use of tools, precision measuring equipment, training, pilot logbook endorsements, or the use of technical data not contained in the AD. These 25 hours TIS checks are additional measures to ensure that a crack that is visible without the aid of a magnifying glass has not developed during the time between maintenance inspections. However, this AD does not require visual checks at intervals of 4 months as specified by the SB, dated March 29, 1993. Due to the criticality of the main rotor blades and the short compliance times, this rule must be issued immediately to correct an unsafe condition in aircraft.

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.

Comments Invited
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 notice must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 93-SW-16-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."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, 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 - AIRWORTHINESSDIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

39.13 - [AMENDED]
2. Section 39.13 is amended by adding the following new airworthiness directive:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Assistant Chief Counsel, Attention: Rules Docket No. 93-SW-16-AD, 2601 Meacham Boulevard, Room 663, Fort Worth, Texas 76137.

Ms. Lirio Liu, Aerospace Engineer, Los Angeles Aircraft Certification Office, FAA, Transport Airplane Directorate, 3229 East Spring Street, Long Beach, California 90806-2425, telephone (310) 988-5229, fax (310) 988-5210.