AD Amdt-39-9177

[Federal Register Volume 60, Number 53 (Monday, March 20, 1995)]
[Rules and Regulations]
[Pages 14619-14621]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 95-6684]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-SW-22-AD; Amendment 39-9177; AD 95-06-07]


Airworthiness Directives; Robinson Helicopter Company Model R22 
Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to Robinson Helicopter Company (RHC) Model R22 
helicopters, that currently requires an initial dye penetrant 
inspection of the main rotor drive forward flexplate (flexplate), and 
repetitive visual inspections of certain installed flexplates. This 
amendment is prompted by three accidents reported by the airworthiness 
authority of Australia involving failure of the flexplate, located 
between the main rotor gearbox and clutch assembly. The actions 
specified by this AD are intended to prevent failure of the flexplate, 
failure of the main rotor drive system, and subsequent loss of control 
of the helicopter.

DATES: Effective April 4, 1995.
    Comments for inclusion in the Rules Docket must be received on or 
before May 19, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 94-SW-22-AD, 2601 Meacham Boulevard, Room 663, Fort 
Worth, Texas 76137-4298.

FOR FURTHER INFORMATION CONTACT: Ms. Elizabeth Bumann, Aerospace 
Engineer, Los Angeles Aircraft Certification Office, Propulsion Branch, 
FAA, 3960 Paramount Blvd., Lakewood, California 90712, telephone (310) 
627-5265, fax (310) 627-5210.

SUPPLEMENTARY INFORMATION: On May 18, 1994, the FAA issued Priority 
Letter AD 94-11-01, applicable to RHC Model R22 helicopters, to require 
an initial dye penetrant inspection of the flexplate on all RHC Model 
R22 helicopters, and repetitive visual inspections of flexplates that 
have been in service for 2 or more years or 500 or more hours time-in-
service (TIS). That action was prompted by three accidents reported by 
the airworthiness authority of Australia involving failure of the 
flexplate. In one accident, the flexplate fractured during 
[[Page 14620]] normal cruise flight releasing several fragments, some 
of which punctured the fuel tank. A metallurgical report issued by the 
airworthiness authority of Australia suggests that the failures 
resulted from fatigue cracking that initiated at areas of intergranular 
pitting corrosion on the edge of the flexplates. The FAA has determined 
that any crack, nick, or corrosion in the flexplate creates an unsafe 
condition and should be corrected. That condition, if not corrected, 
could result in failure of the flexplate, failure of the main rotor 
drive system, and subsequent loss of control of the helicopter.
    Since the issuance of that AD, the FAA has received information 
indicating that flexplates, part number (P/N) A193-1 without bonded 
washers, and P/N A947-1 with bonded washers, may have been subjected to 
paint overspray at Robinson Helicopter Company when they were painting 
hardware adjacent to the flexplate. Damage to flexplate edges with 
paint overspray could result in corrosion due to the retention of 
contaminants under the paint. Robinson Helicopter Company has revised 
their inspection procedures to ensure that subsequently-produced 
flexplates are not subject to the paint overspray. This corrective 
procedure was implemented with the production of flexplate, P/N A947-
1E. In addition, flexplate, P/N A947-1E is stronger and more resistant 
to corrosion damage than the previously-designed flexplates. Therefore, 
the initial dye penetrant inspection for cracks and repetitive visual 
inspections for nicks, cracks, or corrosion may be terminated upon 
installation of this improved flexplate or a subsequent FAA-approved 
revision to P/N A947-1E.
    The reference to the flexplate's TIS in paragraph (b) of the 
Priority Letter AD has been clarified to require that the repetitive 
visual inspections in paragraph (d) of the AD be conducted upon 
reaching 2 years or 500 hours TIS on the flexplate. If the flexplate 
TIS cannot be determined through a review of the log book, the 
helicopter TIS must be used to determine the TIS of the flexplate.
    Paragraph (c) has been revised to delete the reference to the 
repetitive visual inspections for flexplates used to replace those that 
were determined to have cracks as a result of the inspection of 
paragraph (a) of the Priority Letter AD. This deletion changes the 
lettering of the subsequent paragraphs. The FAA has determined that 
these changes will neither increase the economic burden on any operator 
nor increase the scope of the AD.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Robinson Helicopter Company Model R-22 
helicopters of the same type design, this AD supersedes Priority Letter 
AD 94-11-01, to require a one-time dye penetrant inspection of the 
flexplate, P/N A193-1 without bonded washers and P/N A947-1 with bonded 
washers, for cracks within the next 25 hours TIS, and replacement if a 
crack is found. Additionally, for flexplates that have been in service 
for 2 or more years or 450 or more hours TIS, repetitive visual 
inspections of the flexplate for nicks, cracks, or corrosion are 
required at intervals not to exceed 50 hours TIS. This AD also provides 
for repair of the flexplate if a nick or corrosion is found, or 
replacement if a crack is found. The flexplate connects the gearbox and 
the clutch shaft, and failure of the flexplate could lead to failure of 
the driveshaft and loss of power to the rotor system. Due to the 
critical need for the flexplate to ensure the continued safe flight of 
the affected helicopters, 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 rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 94-SW-22-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--AIRWORTHINESS DIRECTIVES

    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.

[[Page 14621]]

Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding a new airworthiness 
directive (AD), Amendment 39-9177, to read as follows:

AD 95-06-07 Robinson Helicopter Company: Amendment 39-9177. Docket 
Number 94-SW-22-AD. Supersedes Priority Letter AD 94-11-01, issued 
May 18, 1994.

    Applicability: Model R22 helicopters, with forward flexplate 
(flexplate), part number (P/N) A947-1 with bonded washers, or P/N 
A193-1 without bonded washers, installed, certificated in any 
category. Flexplate, P/N A947-1E and subsequent FAA-approved 
revisions to P/N A947-1, is exempt from the requirements of this AD.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the flexplate, failure of the main rotor 
drive, and subsequent loss of control of the helicopter, accomplish 
the following:
    (a) Within the next 25 hours time-in-service (TIS) after the 
effective date of this airworthiness directive (AD), accomplish the 
following:
    (1) With the clutch disengaged, support the forward end of the 
clutch shaft, P/N A166-1, remove the flexplate, and record the shim 
locations for use during reinstallation.
    (i) Replace any flexplate that does not have eight bonded 
washers (two per arm) with an airworthy flexplate, P/N A947-1E or a 
subsequent FAA-approved revision to P/N A947-1.
    (ii) For those flexplates that have eight bonded washers (two 
per arm), comply with the following:
    (2) Remove all coating down to bare metal from the outer edges 
of the flexplate to approximately 0.125 inches inward, but in no 
case within 0.50 inches of the bonded washers, using Scotch Brite or 
600 grit sand paper. Do not use a chemical paint stripper since it 
may adversely affect the adhesive that bonds the washers to the 
flexplate.
    (3) Inspect the outer edges of the flexplate for cracks, 
avoiding the bonded washers, using a dye penetrant inspection method 
in accordance with Appendix I of this AD. If the dye penetrant 
contacts the bonded washers, remove the solution from the bonded 
washers within 1 minute since longer exposure may adversely affect 
the adhesive.
    (i) If a crack is found, replace the flexplate with an airworthy 
flexplate, P/N A947-1E or a subsequent FAA-approved revision to P/N 
A947-1.
    (ii) If no crack is found, paint the bare edge area of the 
flexplate with an even coat of zinc-chromate or epoxy primer. Do not 
paint the bare metal surface of the bonded washers.
    (4) Reinstall the flexplate and ensure sheave and clutch shaft 
angle are properly aligned in accordance with the applicable 
maintenance manual.
    (b) For those helicopters with flexplates that have less than 2 
years or 450 hours TIS, accomplish the following prior to or upon 
reaching 2 years or 500 hours TIS, and thereafter at intervals not 
to exceed 50 hours TIS from the last inspection; for those 
helicopters with flexplates that have 2 years or more or 450 hours 
or more TIS, accomplish the following at intervals not to exceed 50 
hours TIS from the last inspection. (If the flexplate TIS cannot be 
determined through a review of the maintenance records, then use the 
helicopter TIS as the TIS of the flexplate).
    (1) Remove the flexplate in accordance with the applicable 
maintenance manual.
    (2) Clean the flexplate using a solvent (e.g., methyl-ethyl 
ketone or naphtha).
    (3) Inspect the flexplate for nicks, cracks, or corrosion using 
a 10-power or higher magnifying glass, paying close attention to the 
edges of the flexplate.
    (i) If a crack is found, replace the flexplate with an airworthy 
flexplate, P/N A947-1E or a subsequent FAA-approved revision to P/N 
A947-1, in accordance with the applicable maintenance manual.
    (ii) If a nick or corrosion is found, repair the flexplate in 
accordance with the applicable maintenance manual.
    (iii) Paint any bare edges of the flexplate with an even coat of 
zinc-chromate or epoxy primer. Do not paint the bare metal surface 
of the bonded washers.
    (iv) If any nick or corrosion cannot be repaired within the 
rework limits specified in the applicable maintenance manual, 
replace the flexplate with an airworthy flexplate, P/N A947-1E or a 
subsequent FAA-approved revision to P/N A947-1, in accordance with 
the applicable maintenance manual.
    (4) Reinstall the flexplate and ensure sheave and clutch shaft 
are properly aligned in accordance with the applicable maintenance 
manual.
    Note 1: Robinson Helicopter Company R22 Maintenance Manual, 
Change 14, dated March 14, 1994, pertains to this AD.

    (c) If a crack, nick, or corrosion is found on the flexplate as 
a result of the inspections required by this AD, report a 
description of the crack, nick, or corrosion, the total TIS, and the 
operating conditions to the Manager, Propulsion Branch, Los Angeles 
Aircraft Certification Office, FAA. Reporting requirements have been 
approved by the Office of Management and Budget and assigned control 
number 2120-0056.
    (d) Installation of a flexplate, P/N A947-1E or a subsequent 
FAA-approved revision to P/N A947-1, constitutes terminating action 
for the requirements of this AD.
    (e) An alternative method of compliance or adjustment of 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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles Aircraft Certification Office.

    (f) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the helicopter to a location where 
the requirements of this AD can be accomplished.
    (g) This amendment becomes effective on April 4, 1995.
Appendix I--Dye Penetrants

    Several dye penetrant type inspection kits are now available 
that will reveal the presence of surface cracks or defects and 
subsurface flaws that extend to the surface of the part being 
inspected. These penetrant type inspection methods are considered 
acceptable, provided the part being inspected has been thoroughly 
cleaned, all areas are readily accessible for viewing, and the 
manufacturer's recommendations as to the method of application are 
closely followed.
    a. Cleaning. An inspection is initiated by first cleaning the 
surface to be inspected of dirt, loose scale, oil, and grease. 
Precleaning may usually be accomplished by vapor degreasing or with 
volatile cleaners. Use a volatile cleaner as it will evaporate from 
the defects before applying the penetrant dye. Sand blasting is not 
as desirable a cleaning method, since surface indications may be 
obscured. It is not necessary to remove anodic films from parts to 
be inspected, since the dye readily penetrates such films. Special 
procedures for removing the excess dye should be followed.
    b. Application of Penetrant. The penetrant is applied by 
brushing, spraying, or by dipping and allowing to stand for a 
minimum of 2 minutes. Dwell time may be extended up to 15 minutes, 
depending upon the temperature of the part and fineness of the 
defect or surface condition. Parts being inspected should be dry and 
heated to at least 70 deg. F, but not over 130 deg. F. Very small 
indications require increased penetration periods.
    c. Removal of Dye Penetrant. Surplus penetrant is usually 
removed by application of a special cleaner or remover, or by 
washing with plain water and allowing the part to dry. Water rinse 
may also be used in conjunction with the remover, subject to the 
manufacturer's recommendations.
    d. Application of Developer. A light and even coat of developer 
is applied by spraying, brushing, or dipping. When dipping, avoid 
excess accumulation. Penetrant that has penetrated into cracks or 
other openings in the surface of the material will be drawn out by 
the developer resulting in a bright red indication. Some idea of the 
size of the defect may be obtained after experience by watching the 
size and rate of growth of the indication.

    Issued in Fort Worth, Texas, on March 10, 1995.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 95-6684 Filed 3-17-95; 8:45 am]
BILLING CODE 4910-13-P