AD Amdt-39-11127

[Federal Register Volume 64, Number 70 (Tuesday, April 13, 1999)]
[Rules and Regulations]
[Pages 17964-17966]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 99-9132]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-SW-25-AD; Amendment 39-11127; AD 99-07-18]
RIN 2120-AA64


Airworthiness Directives; Robinson Helicopter Company Model R44 
Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This document publishes in the Federal Register an amendment 
adopting Airworthiness Directive (AD) 99-07-18 which was sent 
previously to all known U.S. owners and operators of Robinson 
Helicopter Company (RHC) Model R44 helicopters by individual letters. 
This AD requires, before further flight, inserting a Special Pilot 
Caution into the Normal Procedures section of the Rotorcraft Flight 
Manual (RFM). This amendment is prompted by several reports of sprag 
clutch assemblies with cracked or fractured sprag ends. The sprag 
clutch failures, determined to be due to a change in the manufacturing 
process, could result in loss of main rotor revolutions-per-minute 
(RPM) during autorotations. The intent of this AD is to alert pilots of 
the potential for the sprag clutch failing to overrun during 
autorotation, loss of main rotor RPM, and subsequent loss of control of 
the helicopter.

DATES: Effective April 28, 1999, to all persons except those persons to 
whom it was made immediately effective by Priority Letter AD 99-07-18, 
issued on March 26, 1999, which contained the requirements of this 
amendment.
    Comments for inclusion in the Rules Docket must be received on or 
before June 14, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 99-SW-25-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 (562) 627-5210.

SUPPLEMENTARY INFORMATION: On March 26, 1999, the FAA issued Priority 
Letter AD 99-07-18, applicable to RHC Model R44 helicopters, which 
requires, before further flight, inserting a Special Pilot Caution into 
the Normal Procedures section of the RFM. That action was prompted by 
several reports of sprag clutch assemblies, including one from wreckage 
of an accident that occurred within the past year, with cracked or 
fractured sprag ends. The sprag clutch failures, determined to be due 
to a change in the manufacturing process, could result in loss of main 
rotor RPM during autorotations. The intent of that priority letter AD 
is to alert pilots of the potential for the sprag clutch failing to 
overrun during autorotation, loss of main rotor RPM, and subsequent 
loss of control of the helicopter.
    The FAA has reviewed Robinson Helicopter Company R44 Service 
Bulletin SB-32, dated March 22, 1999, which describes procedures for 
checking whether sprag clutches with certain serial numbers are 
installed and replacing certain serial numbered sprag clutches, and 
inserting a Special Pilot Caution in the Normal Procedures section of 
the RFM.
    Since the unsafe condition described is likely to exist or develop 
on other RHC Model R44 helicopters of the same

[[Page 17965]]

type design, the FAA issued Priority Letter AD 99-07-18 to alert pilots 
of the potential for the sprag clutch failing to overrun during 
autorotation due to the failure of the sprags within the sprag clutch 
assembly and loss of main rotor RPM. The AD requires, before further 
flight, inserting a Special Pilot Caution into the Normal Procedures 
section of the RFM which primarily addresses autorotation maneuvers and 
a before every flight sprag clutch (split tach needles) check for 
proper function of the sprag clutch. Inserting the Special Pilot 
Caution is an interim action. The FAA will issue an AD to supersede 
this AD and require replacing the clutch assembly when parts become 
available from the manufacturer. The short compliance time involved is 
required because the previously described critical unsafe condition can 
adversely affect the structural integrity of the helicopter. Therefore, 
inserting a Special Pilot Caution into the Normal Procedures section of 
the RFM is required before further flight, and this AD must be issued 
immediately.
    Since it was found that immediate corrective action was required, 
notice and opportunity for prior public comment thereon were 
impracticable and contrary to the public interest, and good cause 
existed to make the AD effective immediately by individual letters 
issued on March 26, 1999, to all known U.S. owners and operators of RHC 
Model R44 helicopters. These conditions still exist, and the AD is 
hereby published in the Federal Register as an amendment to section 
39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it 
effective to all persons.
    The FAA estimates that 200 helicopters of U.S. registry will be 
affected by this AD, that it will take approximately 0.5 work hour per 
helicopter to insert the caution into the RFM, and that the average 
labor rate is $60 per work hour. Based on these figures, the total cost 
impact of the AD on U.S. operators is estimated to be $6,000.

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 No. 99-SW-25-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 adding a new airworthiness directive 
to read as follows:

AD 99-07-18  Robinson Helicopter Company: Amendment 39-11127. Docket 
No. 99-SW-25-AD.

    Applicability: Model R44 helicopters, serial numbers (S/N) 0001 
through 0541, 0543, 0556, and 0565, with sprag clutch, part number 
(P/N) C188-3, S/N's 0003 through 0452, 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 
otherwise 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 request approval for an 
alternative method of compliance in accordance with paragraph (b) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required before further flight, unless accomplished 
previously.
    To alert pilots of the potential for the sprag clutch failing to 
overrun during autorotation due to failure of the sprags within the 
sprag clutch assembly, and loss of main rotor revolutions-per-
minute, accomplish the following:
    (a) Insert either the Special Pilot Caution, revised March 22, 
1999, which is contained in Robinson Helicopter Company R44 Service 
Bulletin SB-32, dated March 22, 1999, or the following Special Pilot 
Caution paragraphs, into the Normal Procedures section of the 
Rotorcraft Flight Manual, between pages P.4-8 and P.4-9:

[[Page 17966]]



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                          SPECIAL PILOT CAUTION
 
Some sprags in overrunning clutches have been found cracked in service.
 A broken sprag could conceivably prevent the clutch from overrunning
 when entering autorotation. Until the clutch in this aircraft has been
 replaced, do not enter practice autorotations by rapidly closing or
 ``chopping'' the throttle. ``Chopping'' the throttle could result in a
 sudden loss of rotor RPM if the clutch failed to disengage.
 
Enter autorotation by first lowering collective and then rolling off
 just enough throttle to produce a small visible split between the rotor
 and engine tachometer needles. If the clutch fails to disengage,
 immediately complete a power recovery. Perform hovering autos only
 after checking the function of the overrunning sprag clutch prior to
 lift-off, then smoothly rolling off the throttle from a low hover with
 the skids no more than two feet above the ground.
 
Be sure to perform the sprag clutch check (split tach needles) before
 every flight, not just the first flight of the day.
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    (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 a 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.

    (c) Special flight permits may be issued in accordance with 
Secs. 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 April 28, 1999 to all 
persons except those persons to whom it was made immediately 
effective by Priority Letter AD 99-07-18, issued March 26, 1999, 
which contained the requirements of this amendment.

    Issued in Fort Worth, Texas, on April 5, 1999.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 99-9132 Filed 4-12-99; 8:45 am]
BILLING CODE 4910-13-P