Airworthiness Directives; Robinson Helicopter Company (RHC) Model R44 Helicopters

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-SW-25-AD; Amendment 39-10712; AD 98-12-19]

RIN 2120-AA64

Airworthiness Directives; Robinson Helicopter Company (RHC) 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) 98-12-19 which was sent

previously to all known U.S. owners and operators of RHC Model R44

helicopters by individual letters. This AD requires, within 5 hours

TIS, a dye penetrant inspection of each main rotor blade skin (blade

skin) around both inboard trim tab alignment rivet holes. Thereafter, a

repetitive visual inspection of the blade skin around both inboard trim

tab alignment rivet holes is required prior to the first flight of each

day or at intervals not to exceed 5 hours TIS, whichever occurs first.

This amendment is prompted by an incident in which a crack in the main

rotor blade resulted in a forced landing. Subsequent investigations

revealed that the manufacturing process utilized to drill the trim tab

alignment rivet holes in the blade skin can allow a fatigue crack to

originate at these holes and propagate in the skin. This condition, if

not corrected, could result in failure of the main rotor blade and

subsequent loss of control of the helicopter.

DATES: Effective August 28, 1998, to all persons except those persons

to whom it was made immediately effective by priority letter AD 98-12-

19, issued on June 2, 1998, which contained the requirements of this

amendment.

Comments for inclusion in the Rules Docket must be received on or

before October 13, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Office of the Regional Counsel, Southwest Region,

Attention: Rules Docket No. 98-SW-25-AD, 2601 Meacham Blvd., Room 663,

Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Mr. Fred Guerin, Aerospace Engineer,

FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960

Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5232,

fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: On June 2, 1998, the FAA issued priority

letter AD 98-12-19, applicable to RHC Model R44 helicopters, which

requires, within 5 hours TIS, a dye penetrant inspection of the blade

skin around both inboard trim tab alignment rivet holes. Thereafter, a

repetitive visual inspection of the blade skin around both inboard trim

tab alignment rivet holes is required prior to the first flight of each

day or at intervals not to exceed 5 hours TIS, whichever occurs first.

If a crack is found, this AD requires replacing the main rotor blade

with an airworthy main rotor blade before further flight. That action

was prompted by an incident in which a pilot heard a loud noise and

felt severe vibrations while hovering, resulting in a forced landing.

Upon inspection, a crack was found in a main rotor blade that started

at the mid-span inboard trim tab and ran chordwise to the spar where it

turned along the spar for about an inch. The crack originated from a

trim tab alignment rivet hole in the blade skin. Subsequent

investigations revealed that the manufacturing process utilized to

drill the trim tab alignment rivet holes in the blade skin can allow a

fatigue crack to originate at these holes and propagate in the skin.

This condition, if not corrected, could result in failure of the main

rotor blade and subsequent loss of control of the helicopter.

Since the unsafe condition described is likely to exist or develop

on other RHC Model R44 helicopters of the same type design, the FAA

issued priority letter AD 98-12-19 to prevent failure of the main rotor

blade and subsequent loss of control of the helicopter. The AD

requires, within 5 hours TIS, a dye penetrant inspection of the blade

skin around both inboard trim tab alignment rivet holes. Thereafter, a

repetitive visual inspection of the blade skin around both inboard trim

tab alignment rivet holes is required prior to the first flight of each

day or at intervals not to exceed 5 hours TIS, whichever occurs first.

If a crack is found, this AD requires replacing the main rotor blade

with an airworthy main rotor blade before further flight. Installing a

set of main rotor blades, P/N C016-2, constitutes terminating action

for the requirements of this AD.

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 June 2, 1998, to all

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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 96 helicopters of U.S. registry will be

affected by this AD, that it will take approximately 2 work hours per

helicopter to inspect the blade skin and 10 work hours per helicopter

to replace both main rotor blades and that the average labor rate is

$60 per work hour. Required parts will cost approximately $10,000 per

main rotor blade set. Based on these figures, the total cost impact of

the AD on U.S. operators is estimated to be $1,029,120, assuming one

inspection and replacement of both main rotor blades on all helicopters

with blades which would terminate the requirements of this AD.

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. 98-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:

98-12-19 Robinson Helicopter Company: Amendment 39-10712. Docket

No. 98-SW-25-AD.

Applicability: Model R44 helicopters, serial numbers (S/N) 0002

thru 0486, with main rotor blades, part number (P/N) C016-1,

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 (f) 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 as indicated, unless accomplished

previously.

To detect main rotor blade skin fatigue cracks which originate

from the inboard trim tab alignment rivet holes, that could result

in failure of the main rotor blade and subsequent loss of control of

the helicopter, accomplish the following:

(a) Within the next five hours time-in-service (TIS), perform a

dye penetrant inspection of the blade skin around both inboard trim

tab alignment rivets as follows, referring to Figure 1.

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[GRAPHIC] [TIFF OMITTED] TR13AU98.003

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(1) Remove all paint around both rivets, exposing an area of

approximately \3/4\'' in diameter, at the inboard trim tab on top

and bottom of each blade (4 places per blade). Use 180 grit or finer

abrasive paper, followed by 600 grit or finer paper to eliminate

course sanding marks. Sand only in a spanwise direction. Do not use

chemical paint strippers.

(2) Inspect the blade skin around the rivets on the upper and

lower surfaces (4 locations) using a dye penetrant method.

Note 2: Chordwise cracks in the paint up to 2 inches long which

are located along either inboard or outboard edge of the trim tab

are acceptable.

(b) Clean the sanded areas prepared in accordance with paragraph

(a) of this AD with 111-Trichloroethane or methyl ethyl ketone (MEK)

and then apply clear lacquer to seal the unpainted areas.

Note 3: Do not bend the inboard main rotor blade tabs from their

present position or utilize them for any subsequent blade tracking

adjustment.

(c) Thereafter, prior to the first flight of each day, or at

intervals not to exceed 5 hours TIS, whichever occurs first, using a

5-power or higher magnifying glass, visually inspect the upper and

lower blade skin surfaces around the inboard trim tab rivets (4

locations) for cracks.

(d) If a crack is found, replace the main rotor blade with an

airworthy main rotor blade before further flight.

(e) Installation of a set of main rotor blades, P/N C016-2,

constitutes terminating action for the requirements of this AD.

(f) 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.

(g) Special flight permits will not be issued.

Note 5: Robinson Helicopter Company R44 Service Bulletin SB-27A,

revised May 29, 1998, pertains to the subject of this AD.

(h) This amendment becomes effective on August 28, 1998, to all

persons except those persons to whom it was made immediately

effective by Priority Letter AD 98-12-19, issued June 2, 1998, which

contained the requirements of this amendment.

Issued in Fort Worth, Texas, on August 5, 1998.

Henry A. Armstrong,

Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 98-21706 Filed 8-12-98; 8:45 am]

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