6066 Federal Register / Vol. 63, No. 25 / Friday, February 6, 1998 /Rules and Regulations

(b) Except as provided by paragraph (a)(2)

of this AD, prior to the accumulation of 750

flight hours after the accomplishment of the

actions required by paragraph (a) of this AD:

Perform an inspection to detect discrepancies

(excessive wear or play, improper alignment

or adjustment, or improper clearances) of the

aileron, rudder, and elevator gust locks; and

re-rig the gust lock system; in accordance

with Part 2 of the Accomplishment

Instructions of Jetstream Alert Service

Bulletin HS748–A27–128, dated December

20, 1996.

(1) If no discrepancy is detected, repeat the

inspection and re-rigging required by

paragraph (b) of this AD thereafter at

intervals not to exceed 1,500 flight hours.

(2) If any discrepancy is detected, prior to

further flight, repair in accordance with the

alert service bulletin. Thereafter, repeat the

inspection and re-rigging required by

paragraph (b) of this AD at intervals not to

exceed 1,500 flight hours.

(c) 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,

International Branch, ANM–116, FAA,

Transport Airplane Directorate. Operators

shall submit their requests through an

appropriate FAA Principal Maintenance

Inspector, who may add comments and then

send it to the Manager, International Branch,

ANM–116.

Note 2: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the International Branch,

ANM–116.

(d) 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 airplane to

a location where the requirements of this AD

can be accomplished.

(e) The actions shall be done in accordance

with Jetstream Alert Service Bulletin HS748–

A27–128, dated December 20, 1996. This

incorporation by reference was approved by

the Director of the Federal Register in

accordance with 5 U.S.C. 552(a) and 1 CFR

part 51. Copies may be obtained from AI(R)

American Support, Inc., 13850 McLearen

Road, Herndon, Virginia 20171. Copies may

be inspected at the FAA, Transport Airplane

Directorate, 1601 Lind Avenue, SW., Renton,

Washington; or at the Office of the Federal

Register, 800 North Capitol Street, NW., suite

700, Washington, DC.

Note 3: The subject of this AD is addressed

in British airworthiness directive 008–12–96.

(f) This amendment becomes effective on

February 23, 1998.

Issued in Renton, Washington, on January

30, 1998.

Darrell M. Pederson,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 98–2822 Filed 2–5–98; 8:45 am]

BILLING CODE 4910–13–U

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96–NM–269–AD; Amendment

39–10310; AD 98–03–18]

RIN 2120–AA64

Airworthiness Directives; Fokker

Model F28 Mark 0100 and 0070 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment supersedes

an existing airworthiness directive (AD),

applicable to all Fokker Model F28

Mark 0100 and 0070 series airplanes,

that currently requires revising the

Airplane Flight Manual (AFM) to

include information that will enable the

flightcrew to identify failures of the

emergency direct current (DC)/

alternating current (AC) bus power

supply and to take appropriate

corrective actions. This amendment

requires a new terminating modification

for the existing AFM revisions. This

amendment also requires a new AFM

revision to inform the flightcrew that,

under certain conditions, an ‘‘EMER DC

BUS’’ warning on the multi-function

display unit (MFDU) will occur, and to

take appropriate corrective actions. This

amendment is prompted by the issuance

of mandatory continuing airworthiness

information by a foreign civil

airworthiness authority. The actions

specified by this AD are intended to

prevent failures of the emergency DC/

AC bus power supply, which could

reduce the ability of the flightcrew to

control the airplane.

DATES: Effective March 23, 1998.

The incorporation by reference of

certain publications listed in the

regulations is approved by the Director

of the Federal Register as of March 23,

1998.

ADDRESSES: The service information

referenced in this AD may be obtained

from Fokker Services B.V., Technical

Support Department, P. O. Box 75047,

1117 ZN Schiphol Airport, the

Netherlands. This information may be

examined at the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, Rules Docket,

1601 Lind Avenue, SW., Renton,

Washington; or at the Office of the

Federal Register, 800 North Capitol

Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Norman B. Martenson, Manager,

International Branch, ANM–116, FAA,

Transport Airplane Directorate, 1601

Lind Avenue, SW., Renton, Washington

98055–4056; telephone (425) 227–2110;

fax (425) 227–1149.

SUPPLEMENTARY INFORMATION: A

proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39)

by superseding AD 95–21–10,

amendment 39–9396 (60 FR 53110,

October 12, 1995), which is applicable

to all Fokker Model F28 Mark 0100 and

0070 series airplanes, was published in

the Federal Register on January 16,

1997 (62 FR 2324). The action proposed

to supersede AD 95–21–10 to continue

to require revising the Abnormal and

Normal Procedures Sections of the FAAapproved Airplane Flight Manual

(AFM) to include information that will

enable the flightcrew to identify failures

of the emergency direct current (DC)/

alternating current (AC) bus power

supply and to take appropriate

corrective actions. The action also

proposed to require a modification of

the DC bus transfer system, which

would terminate the existing

requirements for the AFM revisions. In

addition, the action proposed to require

revising the Abnormal Procedures

Section of the AFM to inform the

flightcrew that an ‘‘EMER DC BUS’’

warning on the multi-function display

unit (MFDC) will occur when the

emergency DC bus is transferred to

battery power, and to take appropriate

corrective actions.

Interested persons have been afforded

an opportunity to participate in the

making of this amendment. Due

consideration has been given to the

comments received.

Request to Revise Cost Impact

Information

One commenter supports the

proposed rule, but estimates that the

modification required by this AD will

cost $4,250 per airplane, which is more

than the $3,380 per airplane estimate in

the proposed rule.

The FAA infers that the commenter

requests that the cost impact

information for this AD be revised. The

FAA agrees that cost impact of the

required modification is more than the

estimated $3,380 per airplane contained

in the proposed rule. Since issuance of

the Notice of Proposed Rulemaking

(NPRM), Fokker has issued Service

Bulletin SBF100–24–032, Revision 1,

dated April 25, 1997, and Revision 2,

dated July 28, 1997, to correct minor

errors, and to revise the work hour

estimates and part cost estimates for

accomplishment of the modification.

The estimate for accomplishment of Part

1 of the Accomplishment Instructions of

the service bulletin has been changed
Federal Register / Vol. 63, No. 25 / Friday, February 6, 1998 /Rules and Regulations 6067

from 17 work hours to 22 work hours,

and the estimate for accomplishment of

Part 2 of the Accomplishment

Instructions of the service bulletin has

been changed from 5 work hours to 13

work hours. In addition, the estimate for

parts costs has been changed from a

range of $160 to $2,360, to a range of

$160 to $2,580. The FAA has revised the

cost impact information, below,

accordingly.

The FAA has determined that

accomplishment of the modification in

accordance with the original issue,

Revision 1, or Revision 2 of Fokker

Service Bulletin SBF100–24–032

adequately addresses the identified

unsafe condition. Therefore, this AD has

been revised to include Fokker Service

Bulletin SBF100–24–032, Revision 1,

dated April 25, 1997, and Revision 2,

dated July 28, 1997, as additional

sources of service information.

Request To Extend Compliance Time

for Modification

The Air Transport Association (ATA)

of America, on behalf of one of its

members, requests that the compliance

time for accomplishing the modification

be extended from the proposed 12

months to 18 months. The commenter

states that if it is forced to meet the

proposed 12-month compliance

schedule, approximately 20 of the 40

affected airplanes in its fleet would

require modification in a line

environment or during unscheduled

heavy maintenance visits. The

commenter noted that this would result

in significant additional costs. In

addition, the commenter states that the

modification would be difficult to

accomplish during routine overnight

line station maintenance due to the

complexity of the task and accessibility.

The commenter also noted that the

elapsed time to accomplish the

modification will be twice the service

bulletin estimate of 8 hours, since only

one person at a time could work on this

modification. The commenter further

noted that only three diode failures have

been experienced on its affected fleet of

airplanes since operation commenced in

1989. The commenter considers that

this relatively low failure rate also

supports its request for an extension of

the compliance time.

The FAA does not concur with the

commenter’s request to extend the

compliance time. In developing an

appropriate compliance time for this

action, the FAA considered not only the

degree of urgency associated with

addressing the subject unsafe condition,

but the manufacturer’s and foreign

airworthiness authority’s

recommendations as to an appropriate

compliance time, the availability of

required parts, and the practical aspect

of installing the required modification

within an interval of time that parallels

the normal scheduled maintenance for

the majority of affected operators. The

FAA has determined that the

compliance time, as proposed,

represents the maximum interval of

time allowable for the affected airplanes

to continue to operate prior to

accomplishing the required

modification without compromising

safety. The commenter has not provided

data to substantiate why an extension of

the compliance time would not

compromise safety. The failure rate data

of a single operator does not

substantiate why an extension of the

compliance time would not compromise

safety.

In consideration of all of these factors,

and in consideration of the amount of

time that has already elapsed since

issuance of the original NPRM, the FAA

has determined that further delay of this

modification is not appropriate.

However, under the provisions of

paragraph (g) of the final rule, the FAA

may approve requests for adjustments to

the compliance time if data are

submitted to substantiate that such an

adjustment would provide an acceptable

level of safety.

Conclusion

After careful review of the available

data, including the comments noted

above, the FAA has determined that air

safety and the public interest require the

adoption of the rule with the changes

previously described. The FAA has

determined that these changes will

neither significantly increase the

economic burden on any operator nor

increase the scope of the AD.

Cost Impact

There are approximately 132 Fokker

Model F28 Mark 0100 and 0070 series

airplanes of U.S. registry that will be

affected by this AD.

The actions that are currently

required by AD 95–21–10 take

approximately 1 work hour per airplane

to accomplish, at an average labor rate

of $60 per work hour. Based on these

figures, the cost impact of the

previously required actions on U.S.

operators is estimated to be $7,920, or

$60 per airplane.

The modification of the DC bus

transfer system that is required by this

new AD will take approximately 22

(Part 1 of the Accomplishment

Instructions of the service bulletin) or

13 (Part 2 of the Accomplishment

Instructions of the service bulletin)

work hours per airplane to accomplish,

at an average labor rate of $60 per work

hour. The cost of required parts will

range from $160 to as much as $2,580

per airplane. Based on these figures, the

cost impact of the modification required

by this AD on U.S. operators is

estimated to be between $940 and

$3,900 per airplane.

The AFM revision that is required by

this new AD would take approximately

1 work hour per airplane to accomplish,

at an average labor rate of $60 per work

hour. Based on these figures, the cost

impact of the AFM revision required by

this AD on U.S. operators is estimated

to be $7,920, or $60 per airplane.

The cost impact figures discussed

above are based on assumptions that no

operator has yet accomplished any of

the requirements of this AD action, and

that no operator would accomplish

those actions in the future if this AD

were not adopted.

Regulatory Impact

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.

For the reasons discussed above, I

certify that this action (1) is not a

‘‘significant regulatory action’’ under

Executive Order 12866; (2) is not a

‘‘significant rule’’ under DOT

Regulatory Policies and Procedures (44

FR 11034, February 26, 1979); and (3)

will not have a significant economic

impact, positive or negative, on a

substantial number of small entities

under the criteria of the Regulatory

Flexibility Act. A final evaluation has

been prepared for this action and it is

contained in the Rules Docket. A copy

of it 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, Incorporation by reference,

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:
6068 Federal Register / Vol. 63, No. 25 / Friday, February 6, 1998 /Rules and Regulations

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.

§ 39.13 [Amended]

2. Section 39.13 is amended by

removing amendment 39–9396 (60 FR

53110, October 12, 1995), and by adding

a new airworthiness directive (AD),

amendment 39–10310, to read as

follows:

98–03–18 Fokker: Docket 96–NM–269–AD.

Supersedes AD 95–21–10, Amendment

39–9396.

Applicability: All Model F28 Mark 0100

and 0070 series airplanes, certificated in any

category.

Note 1: This AD applies to each airplane

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

airplanes 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 (g) 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 as indicated, unless

accomplished previously.

To prevent failures of the emergency direct

current (DC)/alternating current (AC) bus

power supply, which could reduce the ability

of the flightcrew to control the airplane,

accomplish the following:

Restatement of Actions Required by AD 95–

21–10, Amendment 39–9396

Note 2: For Model F28 Mark 0070 series

airplanes, on which the procedures specified

in Fokker Service Bulletins SBF100–24–033

and SBF100–24–034 have been

accomplished, the AFM revisions required by

paragraphs (a), (b), and (c) of this AD may be

removed from the AFM.

Note 3: For Model F28 Mark 0100 series

airplanes, on which the procedures specified

in Fokker Service Bulletin SBF100–24–030

have not been accomplished, or on which the

procedures specified in Fokker Service

Bulletin SBF100–24–033 have been

accomplished; the AFM revisions required by

paragraphs (a), (b), and (c) of this AD may be

removed from the AFM.

(a) For all airplanes: Within 7 days after

October 27, 1995 (the effective date of AD

95–21–10, amendment 39–9396), revise the

Abnormal Procedures Section of the FAAapproved Airplane Flight Manual (AFM) to

include the following statement. This may be

accomplished by inserting a copy of this AD

in the AFM.

‘‘Section 4—Abnormal Procedures

Add to Sub-section 4.04—Electrical Power

STANDBY ANNUNCIATOR PANEL RED AC

SUPPLY LIGHT ‘‘ON’’

On overhead electrical panel:

GEN LOAD............................................CHECK

• If all generator loads are approximately

zero:

LOSS OF AC SUPPLY

PROCEDURE...................................APPLY

• If not all generator loads are approximately

zero:

DC EMER BUS SUPPLY TRU3

CIRCUIT BREAKER........................CHECK

• If circuit breaker has tripped:

DC EMER BUS SUPPLY TRU3

CIRCUIT BREAKER.........................RESET

—If reset is unsuccessful:

L and R AUDIO.......................................ALTN

Anticipate the effects of an eventual EMER

DC BUS failure, see EMER DC BUS FAULT

procedure.

• If circuit breaker has not tripped:

L and R AUDIO.......................................ALTN

Anticipate the effects of an eventual EMER

DC BUS failure, see EMER DC BUS FAULT

procedure.’’

(b) For all airplanes: Within 7 days after

October 27, 1995, revise the Normal

Procedures Section of the FAA-approved

AFM to include the following statement. This

may be accomplished by inserting a copy of

this AD in the AFM.

‘‘Section 5—Normal Procedures

Insert in front of Sub-section 5.01.01—Takeoff

• After engine start, select the Standby

Annunciator Panel (SAP) backup mode ON

via the BACKUP p/b at the SAP.

• Keep the SAP in the backup mode for the

whole duration of flight until engine

shutdown.

• Monitor the SAP.

Note: Failure conditions as presented on

the SAP bypass the Flight Warning Computer

(FWC) are not subject to alert inhibition. Be

aware that the red LG light on the SAP will

illuminate in case one or both thrustlever(s)

are below the minimum take-off position and

the landing gear is not down.’’

(c) For all Model F28 Mark 0070 series

airplanes; and Model F28 Mark 0100 series

airplanes, in pre-SBF100–24–009

configuration or in post SBF100–24–030

configuration: Within 7 days after October

27, 1995, revise the Abnormal Procedures

Section of the FAA-approved AFM to include

the following statement. This may be

accomplished by inserting a copy of this AD

in the AFM.

‘‘Section 4—Abnormal Procedures

Add to Sub-section 4.04—Electrical Power

ERRATIC ELECTRICAL SYSTEM

BEHAVIOR

In case of continuous rattling sound,

caused by the fast switching of relays and

accompanied by blanking or erratic behavior

of the three displays on the electric panel:

BATTERIES...SELECT MOMENTARILY OFF,

THEN ON

AFFECTED SYSTEMS......RESTORE IF REQD

If the red AC SUPPLY light on the SAP

comes ON:

SAP RED AC SUPPLY LIGHT ‘ON’

PROCEDURE.................................APPLY’’

New Actions Required by This AD

(d) For Model F28 Mark 0070 and 0100

series airplanes, as listed in Fokker Service

Bulletin SBF100–24–032, dated September

12, 1996, or Revision 1, dated April 25, 1997,

or Revision 2, dated July 28, 1997: Within 12

months after the effective date of this AD,

modify the DC bus transfer system in

accordance with Fokker Service Bulletin

SBF100–24–032, dated September 12, 1996;

or Revision 1, dated April 25, 1997; or

Revision 2, dated July 28, 1997. Prior to

further flight following accomplishment of

this modification, accomplish paragraph (e)

of this AD.

Note 4: For Fokker Model F28 Mark 0070

series airplanes, Fokker Service Bulletin

SBF100–24–032 recommends prior or

concurrent accomplishment of the

procedures specified in Fokker Service

Bulletin SBF100–24–034, dated October 17,

1995, or Revision 1, dated September 12,

1996 (which is currently required by AD 96–

26–03, amendment 39–9866).

(e) Revise the Abnormal Procedures

Section of the FAA-approved AFM to include

the following statement. This may be

accomplished by inserting a copy of this AD

in the AFM.

‘‘Section 4—Abnormal Procedures

Sub-section 4.04.05—Electrical Power—Bus

Equipment List

Insert a marker b in each Bus Equipment

List table, at the top of the column marked:

EMERGENCY—DC.

Add the following note at the beginning of

the affected sub-section:

Note: b When an ‘‘EMER DC BUS’’ fault

is presented on the multi-function display

unit (MFDU), check whether the electric

panel digital readouts are operative.

• If operative, the EMER DC bus is

supplied from the battery chargers via the

batteries for 90 minutes and all services

connected to this bus will remain available.

After this time period, batteries will start to

discharge and the effects of an EMER DC BUS

fault should then be expected.

• If inoperative, continue with the EMER

DC BUS FAULT procedure.

At the bottom of each succeeding page (Bus

Equipment List table) of sub-section 4.04.05,

make a clear reference to the note marked b

located at the beginning of sub-section

4.04.05.’’

(f) Accomplishment of the modification in

accordance with paragraph (d) of this AD

constitutes terminating action for the

requirements of paragraphs (a), (b), and (c) of

this AD. After the modification has been

accomplished, the previously required AFM

revision may be removed from the AFM.

(g) 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,

International Branch, ANM–116, FAA,
Federal Register / Vol. 63, No. 25 / Friday, February 6, 1998 /Rules and Regulations 6069

Transport Airplane Directorate. Operators

shall submit their requests through an

appropriate FAA Principal Maintenance

Inspector, who may add comments and then

send it to the Manager, International Branch,

ANM–116.

Note 5: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the International Branch,

ANM–116.

(h) 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 airplane to

a location where the requirements of this AD

can be accomplished.

(i) The actions shall be done in accordance

with the following Fokker service bulletins,

which contain the specified effective pages:

Service bulletin referenced and date Page No.

Revision level

shown on

page

Date shown on page

SBF100–24–032, September 12, 1996 ................... 1–46 ......................................................................... Original ........ September 12, 1996.

SBF100–24–032, Revision 1, April 25, 1997 .......... 1–4, 7–62 ................................................................ 1 ................... April 25, 1997.

5–6 ........................................................................... Original ........ September 12, 1996.

SBF100–24–032, Revision 2, July 28, 1997 ........... 1–2, 13, 15, 29–30 .................................................. 2 ................... July 28, 1997.

3–4, 7–12, 14, 16–28, 31–62 .................................. 1 ................... April 25, 1997.

5–6 ........................................................................... Original ........ September 12, 1996.

This incorporation by reference was

approved by the Director of the Federal

Register in accordance with 5 U.S.C. 552(a)

and 1 CFR part 51. Copies may be obtained

from Fokker Services B.V., Technical

Support Department, P.O. Box 75047, 1117

ZN Schiphol Airport, the Netherlands.

Copies may be inspected at the FAA,

Transport Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington; or at the

Office of the Federal Register, 800 North

Capitol Street, NW., suite 700, Washington,

DC.

Note 6: The subject of this AD is addressed

in Dutch airworthiness directive BLA 1995–

089/4, dated September 30, 1996.

(j) This amendment becomes effective on

March 23, 1998.

Issued in Renton, Washington, on January

30, 1998.

Stewart R. Miller,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 98–2825 Filed 2–5–98; 8:45 am]

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97–SW–23–AD; Amendment

39–10313; AD 97–15–15]

RIN 2120–AA64

Airworthiness Directives; Eurocopter

France Model SA–365N, SA–365N1,

and SA–366G1 Helicopters

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule; request for

comments.

SUMMARY: This document publishes in

the Federal Register an amendment

adopting Airworthiness Directive (AD)

97–15–15, which was sent previously to

all known U.S. owners and operators of

Eurocopter France Model SA–365N,

SA–365N1, and SA–366G1 helicopters

by individual letters. This AD requires

an inspection of the main gearbox

magnetic plug (magnetic plug) and the

main gearbox oil filter (oil filter) for

ferrous chips; vibration measurements,

if necessary; and replacement of the

main gearbox if a specified quantity of

ferrous chips are discovered, or if

abnormal vibrations are identified at a

certain frequency. This amendment is

prompted by two recent reports of

cracks found in planetary gear shafts

(gear shafts) in main gearboxes that have

not been modified in accordance with

MOD 077244. The actions specified by

this AD are intended to detect cracks in

the gear shaft which could lead to

failure of the gear shaft, failure of the

transmission, and subsequent loss of

control of the helicopter.

DATES: Effective February 23, 1998, to

all persons except those persons to

whom it was made immediately

effective by priority letter AD 97–15–15,

issued on July 18, 1997, which

contained the requirements of this

amendment.

Comments for inclusion in the Rules

Docket must be received on or before

April 7, 1998.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Office of the

Regional Counsel, Southwest Region,

Attention: Rules Docket No. 97–SW–23–

AD, 2601 Meacham Blvd., Room 663,

Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Mr.

Shep Blackman, Aerospace Engineer,

Rotorcraft Standards Staff, Rotorcraft

Directorate, FAA, 2601 Meacham Blvd.,

Fort Worth, Texas 76137, telephone

(817) 222–5296, fax (817) 222–5961.

SUPPLEMENTARY INFORMATION: On July

18, 1997, the FAA issued priority letter

AD 97–15–15, applicable to Eurocopter

France Model SA–365N, SA–365N1,

and SA–366G1 helicopters, which

requires an inspection of the magnetic

plug and the oil filter for ferrous chips;

vibration measurements, if necessary;

and replacement of the main gearbox if

a specified quantity of ferrous chips are

discovered, or if abnormal vibrations are

identified at a certain frequency.

That action was prompted by two

recent reports of cracks found in gear

shafts in main gearboxes, part number

(P/N) 365A32–6000–00, 365A32–6000–

02, 365A32–6001–00, or 366A32–0001–

00, that have not been modified in

accordance with MOD 077244. Upon

inspection, the manufacturer discovered

that 13 main gearbox epicyclic modules

were assembled at the factory with

mismatched planetary gear tooth to ring

gear radii. This produces higher than

normal gear tooth loading stresses

which substantially reduce the fatigue

life of the gear shaft. This condition, if

not corrected, could result in cracks in

the gear shaft, failure of the

transmission, and subsequent loss of

control of the helicopter.

Eurocopter France has issued Telex

Service No. 0035/00188/97, dated July

7, 1997, and Telex Service No. 00037/

00190/97, dated July 9, 1997, which

specify checks of the oil filter after the

last flight of each day for cracks; and

also specify performing vibration

measurements if metal chips are found

on the magnetic plug or in the oil filter,

or if abnormal vibrations are reported by

the crew. The DGAC classified these

service telexes as mandatory, and issued

AD 97–145–042(AB), dated July 10,

1997, and AD 97–164–020(AB), dated

July 16, 1997.

These helicopter models are

manufactured in France and are type

certificated for operation in the United

States under the provisions of section

21.29 of the Federal Aviation

Regulations (14 CFR 21.29) and the

applicable bilateral airworthiness

agreement. Pursuant to this bilateral

airworthiness agreement, the Direction