[Federal Register Volume 64, Number 10 (Friday, January 15, 1999)]
[Rules and Regulations]
[Pages 2558-2559]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-910]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-SW-79-AD; Amendment 39-10991; AD 99-02-02]
RIN 2120-AA64


Airworthiness Directives; Robinson Helicopter Company (RHC) 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 RHC Model R22 helicopters, that currently requires 
initial and repetitive inspections of the forward flexplate (flexplate) 
at specified time intervals. This amendment also supersedes an existing 
priority letter AD that requires, within 25 hours time-in-service (TIS) 
or 15 calendar days, whichever occurs first, replacing the flexplate 
with an airworthy flexplate. This amendment requires the same 
replacement as the priority letter AD. This amendment is prompted by an 
accident in which the flexplate failed, causing loss of main rotor 
drive and rupture of the fuel tank. The actions specified by this AD 
are intended to prevent failure of the flexplate, which could result in 
failure of the main rotor drive system and subsequent loss of control 
of the helicopter.

DATES: Effective February 1, 1999.
    Comments for inclusion in the Rules Docket must be received on or 
before March 16, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 98-SW-79-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Elizabeth Bumann, Aerospace Engineer, 
FAA, Los Angeles Aircraft Certification Office, Propulsion Branch, 3960 
Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5265, 
fax (817) 627-5210.

SUPPLEMENTARY INFORMATION: The FAA issued priority letter AD 94-11-01 
on May 18, 1994 and AD 95-06-07 (60 FR 14619, March 20, 1995) on March 
10, 1995. AD 95-06-07 superseded priority letter AD 94-11-01. Both AD's 
were prompted by three accidents involving failure of the flexplate. 
Both AD's also required an initial dye-penetrant inspection and 
repetitive visual inspections of the flexplate at intervals not to 
exceed 50 hours TIS, after accumulating 500 hours TIS or 2 years 
service life, whichever occurred first. AD 95-06-07 also exempted 
flexplate, part number (P/N) A947-1 E, and subsequent FAA-approved 
revisions, from the requirements of that AD, and provided that 
installation of flexplate, P/N A947-1 E or a subsequent FAA-approved 
revision to that P/N, constituted a terminating action for the 
requirements of that AD.
    After the issuance of AD 95-06-07, another accident occurred in 
which the flexplate, P/N A947-1, failed, causing loss of the main rotor 
drive and rupture of the fuel tank. Prompted by that accident, the FAA 
determined that the repetitive inspections required by AD 95-06-07 did 
not correct the unsafe condition. Therefore, the FAA issued priority 
letter AD 98-14-08 on June 25, 1998, which specifies procedures for 
replacing flexplate, P/N A193-1 or P/N A947-1 A through D, with 
flexplate, P/N A947-1 E or F. Also, the FAA intended that Priority 
Letter AD 98-14-08 (Docket 98-SW-33-AD) supersede AD 95-06-07 (Docket 
94-SW-22-AD), but did not state that in Priority Letter AD 98-14-08. To 
eliminate any confusion, this AD supersedes Priority Letter AD 98-14-08 
(Docket 98-SW-30-AD), and AD 95-06-07, Amendment 39-9177 (Docket 94-SW-
22-AD). This action is intended to prevent failure of the flexplate, 
which could result in failure of the main rotor drive system and 
subsequent loss of control of the helicopter.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other RHC Model R22 helicopters of the same type 
design, this AD supersedes AD 95-06-07 and priority letter AD 98-14-08 
to prevent failure of the flexplate, which could result in failure of 
the main rotor drive system and subsequent loss of control of the 
helicopter. The short compliance time involved is required because the 
previously described critical unsafe condition can adversely affect the 
controllability of the helicopter. Therefore, replacing the flexplate 
with an airworthy flexplate is required within 25 hours TIS or 15 
calendar days, whichever occurs first, and this AD must be issued 
immediately.
    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.
    The FAA estimates that 100 helicopters will be affected by this AD, 
that it will take approximately 1.5 work hours to replace the 
flexplate, and that the average labor rate is $60 per work hour. 
Required parts will cost approximately $536 per helicopter. Based on 
these figures, the total cost impact of the AD on U.S. operators is 
estimated to be $62,600.

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.

[[Page 2559]]

    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. 98-SW-79-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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Amendment 39-9177 (60 FR 
14619, March 20, 1995), and by adding a new airworthiness directive 
(AD), Amendment 39-10991, to read as follows:

AD 99-02-02  Robinson Helicopter Company: Amendment 39-10991. Docket 
No. 98-SW-79-AD. Supersedes AD 95-06-07, Amendment 39-9177, Docket 
No. 94-SW-22-AD, and Priority Letter AD 98-14-08, Docket No. 98-SW-
30-AD.

    Applicability: Model R22 helicopters, with forward flexplate 
(flexplate), part number (P/N) A947-1, A through D, or P/N A193-1, 
installed, certificated in any category.

    Note 1: This AD applies to each helicopter identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For helicopters that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must use the authority 
provided in paragraph (b) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition, or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any helicopter from the applicability of this AD.

    Compliance: Required within 25 hours time-in-service (TIS) or 15 
calendar days, whichever occurs first, unless accomplished 
previously.
    To prevent failure of the flexplate, which could result in 
failure of the main rotor drive system and subsequent loss of 
control of the helicopter, accomplish the following:
    (a) Remove the flexplate and replace it with an airworthy 
flexplate, P/N A947-1 E or F, in accordance with following:
    (1) With the clutch disengaged, support the forward end of the 
clutch shaft, P/N A166-1, and remove the forward flexplate, P/N 
A947-1 or A193-1, and the intermediate flexplate, P/N A947-2 or P/N 
A193-2. Record any shim locations for reinstallation.
    (2) Install a zero TIS forward flexplate, P/N A947-1 E or F, and 
any shims that were noted. Use washers, P/N AN960-516 or AN960-516L, 
under the nut so that 2-4 threads are exposed. Torque the fasteners.
    (3) Inspect the sheave alignment.
    (4) Inspect the clutch shaft, P/N A166-1, angle.
    (5) Reinstall the intermediate flexplate and shim.

    Note 2: Robinson R22 Maintenance Manual, Sections 1.320, 7.230, 
7.240, and 7.330 pertain to paragraphs (a)(2), (a)(3), (a)(4), and 
(a)(5) of this AD, respectively.

    Note 3: Robinson Helicopter Company R22 Service Bulletin SB-75, 
dated November 22, 1994, pertains to the subject of this AD.

    (b) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if 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 4: 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.

    (c) 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.
    (d) This amendment becomes effective on February 1, 1999.

    Issued in Fort Worth, Texas, on January 6, 1999.
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 99-910 Filed 1-14-99; 8:45 am]
BILLING CODE 4910-13-U