Federal Register / Vol. 66, No. 184 / Friday, September 21, 2001 / Rules and Regulations 48535

14Organization for Economic Cooperation and

Development (OECD)–based countries is defined in

appendix A of this part.

15U.S. government-sponsored agencies,

multilateral development banks, and OECD banks

are defined in appendix A of this part.

16An organization may also net positions in

depository receipts against an opposite position in

the underlying equity or identical equity in

different markets, provided that the organization

includes the costs of conversion.

17A portfolio is liquid and well-diversified if: (1)

it is characterized by a limited sensitivity to price

changes of any single equity issue or closely related

group of equity issues held in the portfolio; (2) the

volatility of the portfolio’s value is not dominated

by the volatility of any individual equity issue or

by equity issues from any single industry or

economic sector; (3) it contains a large number of

individual equity positions, with no single position

representing a substantial portion of the portfolio’s

total market value; and (4) it consists mainly of

issues traded on organized exchanges or in wellestablished over-the-counter markets.

(1) Covered debt positions. (i) For purposes

of this section 5, covered debt positions

means fixed-rate or floating-rate debt

instruments located in the trading account or

instruments located in the trading account

with values that react primarily to changes in

interest rates, including certain nonconvertible preferred stock, convertible

bonds, and instruments subject to repurchase

and lending agreements. Also included are

derivatives (including written and purchased

options) for which the underlying instrument

is a covered debt instrument that is subject

to a non-zero specific risk capital charge.

(A) For covered debt positions that are

derivatives, an organization must risk-weight

(as described in paragraph (c)(1)(iii) of this

section) the market value of the effective

notional amount of the underlying debt

instrument or index portfolio. Swaps must be

included as the notional position in the

underlying debt instrument or index

portfolio, with a receiving side treated as a

long position and a paying side treated as a

short position; and

(B) For covered debt positions that are

options, whether long or short, an

organization must risk-weight (as described

in paragraph (c)(1)(iii) of this section) the

market value of the effective notional amount

of the underlying debt instrument or index

multiplied by the option’s delta.

(ii) An organization may net long and short

covered debt positions (including

derivatives) in identical debt issues or

indices.

(iii) An organization must multiply the

absolute value of the current market value of

each net long or short covered debt position

by the appropriate specific risk weighting

factor indicated in Table 2 of this appendix.

The specific risk capital charge component

for covered debt positions is the sum of the

weighted values.

TABLE 2.—SPECIFIC RISK WEIGHTING

FACTORS FOR COVERED DEBT POSITIONS

Category

Remaining maturity (contractual)Weighting

factor (in

percent)

Government ... N/A ................... 0.00

Qualifying ....... 6 months or

less.

0.25

Over 6 months

to 24 months.

1.00

Over 24 months 1.60

Other .............. N/A ................... 8.00

(A) The government category includes all

debt instruments of central governments of

OECD-based countries 14 including bonds,

Treasury bills, and other short-term

instruments, as well as local currency

instruments of non-OECD central

governments to the extent the organization

has liabilities booked in that currency.

(B) The qualifying category includes debt

instruments of U.S. government-sponsored

agencies, general obligation debt instruments

issued by states and other political

subdivisions of OECD-based countries,

multilateral development banks, and debt

instruments issued by U.S. depository

institutions or OECD banks that do not

qualify as capital of the issuing institution.15

This category also includes other debt

instruments, including corporate debt and

revenue instruments issued by states and

other political subdivisions of OECD

countries, that are:

(1) Rated investment-grade by at least two

nationally recognized credit rating services;

(2) Rated investment grade by one

nationally recognized credit rating agency

and not rated less than investment grade by

any other credit rating agency; or

(3) Unrated, but deemed to be of

comparable investment quality by the

reporting organization and the issuer has

instruments listed on a recognized stock

exchange, subject to review by the Federal

Reserve.

(C) The other category includes debt

instruments that are not included in the

government or qualifying categories.

(2) Covered equity positions. (i) For

purposes of this section 5, covered equity

positions means equity instruments located

in the trading account and instruments

located in the trading account with values

that react primarily to changes in equity

prices, including voting or non-voting

common stock, certain convertible bonds,

and commitments to buy or sell equity

instruments. Also included are derivatives

(including written or purchased options) for

which the underlying is a covered equity

position.

(A) For covered equity positions that are

derivatives, an organization must risk weight

(as described in paragraph (c)(2)(iii) of this

section) the market value of the effective

notional amount of the underlying equity

instrument or equity portfolio. Swaps must

be included as the notional position in the

underlying equity instrument or index

portfolio, with a receiving side treated as a

long position and a paying side treated as a

short position; and

(B) For covered equity positions that are

options, whether long or short, an

organization must risk weight (as described

in paragraph (c)(2)(iii) of this section) the

market value of the effective notional amount

of the underlying equity instrument or index

multiplied by the option’s delta.

(ii) An organization may net long and short

covered equity positions (including

derivatives) in identical equity issues or

equity indices in the same market.16

(iii)(A) An organization must multiply the

absolute value of the current market value of

each net long or short covered equity

position by a risk weighting factor of 8.0

percent, or by 4.0 percent if the equity is held

in a portfolio that is both liquid and welldiversified.17 For covered equity positions

that are index contracts comprising a welldiversified portfolio of equity instruments,

the net long or short position is to be

multiplied by a risk weighting factor of 2.0

percent.

(B) For covered equity positions from the

following futures-related arbitrage strategies,

an organization may apply a 2.0 percent risk

weighting factor to one side (long or short)

of each equity position with the opposite side

exempt from charge, subject to review by the

Federal Reserve:

(1) Long and short positions in exactly the

same index at different dates or in different

market centers; or

(2) Long and short positions in index

contracts at the same date in different but

similar indices.

(C) For futures contracts on broadly-based

indices that are matched by offsetting

positions in a basket of stocks comprising the

index, an organization may apply a 2.0

percent risk weighting factor to the futures

and stock basket positions (long and short),

provided that such trades are deliberately

entered into and separately controlled, and

that the basket of stocks comprises at least 90

percent of the capitalization of the index.

(iv) The specific risk capital charge

component for covered equity positions is

the sum of the weighted values.

[61 FR 47373, Sept. 6, 1996, as amended at

62 FR 68068, Dec. 30, 1997; 64 FR 19038,

Apr. 19, 1999; 65 FR 75859, Dec. 5, 2000]

[FR Doc. 01–55528 Filed 9–20–01; 8:45 am]

BILLING CODE 1505–01–D

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001–SW–29–AD; Amendment

39–12443; AD 2001–13–51]

RIN 2120–AA64

Airworthiness Directives; Bell

Helicopter Textron Canada Model

206L–4, 407, and 427 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)

48536 Federal Register / Vol. 66, No. 184 / Friday, September 21, 2001 / Rules and Regulations

2001–13–51, which was sent previously

to all known U.S. owners and operators

of Bell Helicopter Textron Canada

(BHTC) Model 206L–4, 407, and 427

helicopters by individual letters. This

AD requires visually inspecting certain

driveshafts for a crack, a loose bolt or

nut, or red powder residue. If a crack,

a loose bolt or nut, or red powder

residue is found, replacing the

driveshaft before further flight and

notifying the FAA within 10 days is also

required. This amendment is prompted

by a driveshaft failure on a BHTC Model

407 helicopter that resulted in an engine

shutdown and an emergency landing.

Failure of the driveshaft was due to

cracking of the flexframe on the forward

end of the driveshaft. In addition, three

other incidents of a cracked flexframe

on the forward end of the driveshaft on

other Model 407 helicopters have been

reported. The actions specified by this

AD are intended to prevent failure of a

driveshaft, loss of drive to the main

rotor system, and a subsequent

emergency forced landing.

DATES: Effective October 9, 2001, to all

persons except those persons to whom

it was made immediately effective by

Emergency AD 2001–13–51, issued on

June 27, 2001, which contained the

requirements of this amendment.

The incorporation by reference of

certain publications listed in the

regulations is approved by the Director

of the Federal Register as of October 9,

2001. Comments for inclusion in the

Rules Docket must be received on or

before November 20, 2001.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Office of the

Regional Counsel, Southwest Region,

Attention: Rules Docket No. 2001–SW–

29–AD, 2601 Meacham Blvd., Room

663, Fort Worth, Texas 76137. You may

also send comments electronically to

the Rules Docket at the following

address: 9-asw-adcomments@faa.gov.

The applicable service information

may be obtained from Bell Helicopter

Textron Canada, 12,800 Rue de l’Avenir,

Mirabel, Quebec J7J1R4, telephone (450)

437–2862 or (800) 363–8023, fax (450)

433–0272. The service information may

also be obtained by e-mailing a request

to pselight@bellhelicopter.textron.com.

This information may be examined at

the FAA, Office of the Regional Counsel,

Southwest Region, 2601 Meacham

Blvd., Room 663, Fort Worth, Texas; or

at the Office of the Federal Register, 800

North Capitol Street, NW., suite 700,

Washington, DC.

FOR FURTHER INFORMATION CONTACT: Paul

Madej, Aviation Safety Engineer, FAA,

Rotorcraft Directorate, Rotorcraft

Standards Staff, Fort Worth, Texas

76193–0110, telephone (817) 222–5125,

fax (817) 222–5961.

SUPPLEMENTARY INFORMATION: On June

27, 2001, the FAA issued Emergency AD

2001–13–51 for BHTC Model 206L–4,

407, and 427 helicopters, which

requires the following if driveshaft, part

number 206–340–300–105, has ever

been installed on a BHTC Model 407

helicopter:

• At specified hours time-in-service

(TIS), visually inspect each driveshaft

for a crack, a loose bolt or nut, or red

powder residue.

• Before further flight, replace the

driveshaft with an airworthy driveshaft

if a crack, a loose bolt or nut, or red

powder residue is found. Within 10

days, notify the Manager, Regulations

Group, FAA, of the helicopter serial

number, driveshaft serial number, and

driveshaft hours TIS.

• After the effective date of this AD,

interchanging a driveshaft between

different helicopter models is prohibited

if that driveshaft has ever been installed

on a BHTC Model 407 helicopter.

That action was prompted by a

driveshaft failure on a BHTC Model 407

helicopter that resulted in an engine

shutdown and an emergency landing.

Failure of the driveshaft was due to

cracking of the flexframe on the forward

end of the driveshaft. The BHTC Model

206L–4 and 427 helicopters use the

same part-numbered driveshaft. In

addition, three other incidents of a

cracked flexframe on the forward end of

the driveshaft on other Model 407

helicopters have been reported. This

condition, if not detected, could result

in failure of a driveshaft, loss of drive

to the main rotor system, and a

subsequent emergency forced landing.

Transport Canada, which is the

airworthiness authority for Canada,

notified the FAA that an unsafe

condition may exist on BHTC Model

407 helicopters. Transport Canada

advises that during flight the driveshaft,

P/N 206–340–300–105, failed causing

engine shutdown and a forced landing.

Three other incidents of the cracked

flexframe on the forward end of the

BHTC Model 407 driveshafts were also

reported. Pending further corrective

action, Transport Canada determined

that a one-time visual inspection for any

obvious discrepancy of the driveshaft is

warranted.

The FAA has reviewed BHTC Alert

Service Bulletin No. 407–01–43, dated

June 8, 2001 (ASB), which describes

procedures for a one-time inspection of

the engine-to-transmission driveshaft, P/

N 206–340–300–105. Transport Canada

classified this ASB as mandatory and

issued AD CF–2001–24, dated June 11,

2001, to ensure the continued

airworthiness of BHTC Model 407

helicopters in Canada.

Since the unsafe condition described

is likely to exist or develop on other

BHTC Model 206L–4, 407, and 427

helicopters of the same type designs, the

FAA issued Emergency AD 2001–13–51

to prevent failure of a driveshaft, loss of

drive to the main rotor system, and a

subsequent emergency forced landing.

The AD requires the actions specified

above. The inspections must be

accomplished in accordance with the

ASB described previously. The short

compliance time involved is required

because the previously described

critical unsafe condition can adversely

affect the structural integrity and

controllability of the helicopter.

Therefore, visually inspecting the

driveshaft at the specified time intervals

and replacing the driveshaft, if

necessary, 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 June 27, 2001 to all

known U.S. owners and operators of

BHTC Model 206L–4, 407, and 427

helicopters. These conditions still exist,

and the AD is hereby published in the

Federal Register as an amendment to 14

CFR 39.13 to make it effective to all

persons. However, a few editorial

changes have been made to the AD. The

zip code listed for the manufacturer has

been corrected and an e-mail address for

obtaining service information has been

added. Also, due to confusion expressed

by an operator, paragraph (a)(1)(i) has

been changed to clarify that the

notification requirement is necessary

only if a crack, a loose bolt or nut, or

red powder residue is found during the

visual inspection. The FAA has

determined that these changes will

neither increase the economic burden

on an operator nor increase the scope of

the AD

The FAA estimates that 488

helicopters of U.S. registry will be

affected by this AD, that it will take

approximately 4 work hours per

helicopter to visually inspect the

driveshaft. 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 $117,120,

assuming that each driveshaft is

inspected once.

Federal Register / Vol. 66, No. 184 / Friday, September 21, 2001 / Rules and Regulations 48537

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 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 mailed

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. 2001–SW–

29–AD.’’ The postcard will be date

stamped and returned to the

commenter.

The regulations adopted herein will

not have a substantial direct effect 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, it is

determined that this final rule does not

have federalism implications under

Executive Order 13132.

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, 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:

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

adding a new airworthiness directive to

read as follows:

2001–13–51 Bell Helicopter Textron

Canada: Amendment 39–12443. Docket

No. 2001–SW–29–AD.

Applicability: Model 206L–4, 407, and 427

helicopters, with engine-to-transmission

driveshaft assembly (driveshaft), part number

206–340–300–105, 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 (c) 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 failure of a driveshaft, loss of

drive to the main rotor system, and a

subsequent emergency forced landing,

accomplish the following:

(a) If a driveshaft has ever been installed

on a Bell Helicopter Textron Canada (BHTC)

Model 407 helicopter, within 25 hours timein-service (TIS) for driveshafts with 1000 or

more hours TIS and for driveshafts with 1000

or less hours TIS that have been removed or

installed since helicopter delivery, and

within 300 hours TIS for driveshafts with

less than 1000 hours TIS that have never

been removed or installed since helicopter

delivery:

(1) Visually inspect each driveshaft for a

crack, loose bolt or nut, or red powder

residue, in accordance with the

Accomplishment Instructions, paragraphs 1

through 7 of Bell Helicopter Textron Alert

Service Bulletin 407–01–43, dated June 8,

2001 (ASB).

(2) Before further flight, if a crack, a loose

bolt or nut, or red powder residue is found,

replace the driveshaft with an airworthy

driveshaft.

(i) If a crack, a loose bolt or nut, or red

powder residue is found, notify the Manager,

Regulations Group, FAA, Rotorcraft

Directorate, Fort Worth, Texas 76193–0111,

of the helicopter serial number, driveshaft

serial number, and driveshaft hours TIS

within 10 days.

(ii) Reporting requirements have been

approved by the Office of Management and

Budget and assigned OMB control number

2120–0056.

(b) After the effective date of this AD,

interchanging a driveshaft between different

helicopter models is prohibited if that

driveshaft has ever been installed on a BHTC

Model 407 helicopter.

(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, Regulations

Group, Rotorcraft Directorate, FAA.

Operators shall submit their requests through

an FAA Principal Maintenance Inspector,

who may concur or comment and then send

it to the Manager, Regulations Group.

Note 2: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Manager, Regulations

Group.

(d) Special flight permits may be issued in

accordance with 14 CFR 21.197 and 21.199

to operate the helicopter to a location where

the requirements of this AD can be

accomplished.

(e) The visual inspection shall be done in

accordance with the Accomplishment

Instructions, paragraphs 1 through 7 of Bell

Helicopter Textron Alert Service Bulletin

407–01–43, dated June 8, 2001. 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 Bell

Helicopter Textron Canada, 12,800 Rue de

l’Avenir,Mirabel, Quebec J7J1R4, telephone

(450) 437–2862 or (800) 363–8023, fax (450)

433–0272, or by e-mailing a request to

pselight@bellhelicopter.textron.com. Copies

may be inspected at the FAA, Office of the

Regional Counsel, Southwest Region, 2601

Meacham Blvd., Room 663, Fort Worth,

Texas; or at the Office of the Federal Register,

800 North Capitol Street, NW., suite 700,

Washington, DC.

(f) This amendment becomes effective on

October 9, 2001, to all persons except those

persons to whom it was made immediately

effective by Emergency AD 2001–13–51,

issued June 27, 2001, which contained the

requirements of this amendment.

48538 Federal Register / Vol. 66, No. 184 / Friday, September 21, 2001 / Rules and Regulations

Note 3: The subject of this AD is addressed

in Transport Canada (Canada) AD CF–2001–

24, dated June 11, 2001.

Issued in Fort Worth, Texas, on September

12, 2001.

Eric Bries,

Acting Manager, Rotorcraft Directorate,

Aircraft Certification Service.

[FR Doc. 01–23416 Filed 9–20–01; 8:45 am]

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000–NM–385–AD; Amendment

39–12444; AD 2001–19–04]

RIN 2120–AA64

Airworthiness Directives; Boeing

Model 767–200 and –300 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule; request for

comments.

SUMMARY: This amendment adopts a

new airworthiness directive (AD) that is

applicable to certain Boeing Model 767–

200 and –300 series airplanes. This

action requires repetitive inspections to

find discrepancies of the barrel nuts that

attach the vertical fin to body section

48, and follow-on actions. For certain

airplanes, this action requires

replacement of certain bolts with new

bolts. This action also provides for

optional terminating actions for the

repetitive inspections. This action is

necessary to find and fix corroded,

cracked or broken barrel nuts that attach

the vertical fin to body section 48,

which could result in reduced structural

integrity of the vertical fin attachment

joint, loss of the vertical fin, and

consequent loss of controllability of the

airplane. This action is intended to

address the identified unsafe condition.

DATES: Effective October 9, 2001.

The incorporation by reference of

certain publications listed in the

regulations is approved by the Director

of the Federal Register as of October 9,

2001.

Comments for inclusion in the Rules

Docket must be received on or before

November 20, 2001.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–114,

Attention: Rules Docket No. 2000–NM–

385–AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055–4056.

Comments may be inspected at this

location between 9 a.m. and 3 p.m.,

Monday through Friday, except Federal

holidays. Comments may be submitted

via fax to (425) 227–1232. Comments

may also be sent via the Internet using

the following address: 9-anmiarcomment@faa.gov. Comments sent

via fax or the Internet must contain

‘‘Docket No. 2000–NM–385–AD’’ in the

subject line and need not be submitted

in triplicate. Comments sent via the

Internet as attached electronic files must

be formatted in Microsoft Word 97 for

Windows or ASCII text.

The service information referenced in

this AD may be obtained from Boeing

Commercial Airplane Group, P.O. Box

3707, Seattle, Washington 98124–2207.

This information may be examined 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.

FOR FURTHER INFORMATION CONTACT: John

Craycraft, Aerospace Engineer, Airframe

Branch, ANM–120S, FAA, Seattle

Aircraft Certification Office, 1601 Lind

Avenue, SW., Renton, Washington

98055–4056; telephone (425) 227–2782;

fax (425) 227–1181.

SUPPLEMENTARY INFORMATION: The FAA

has received several reports of corroded

and/or broken barrel nuts on certain

Boeing Model 767–200 and –300 series

airplanes. One operator indicated that

cracked and bulging sealant of two

attachment barrel nuts of the vertical fin

at body section 48 was found on an

airplane having 9,795 total flight hours

and 4,184 total flight cycles. A torque

check confirmed low torque at these

locations, and removal of the sealant

revealed that both barrel nuts were

corroded and broken. Further

investigation revealed that the broken

barrel nuts fractured due to stress

corrosion cracks that started at corrosion

pits. Examination of the attachment

bolts showed inadequate sealant on the

bolt threads and shank. The lack of

sealant initiated galvanic corrosion

between the H–11 steel barrel nut and

the Inconel bolt, which created the

corrosion pits. Nuts made of H–11 steel

alloy are susceptible to stress corrosion

cracking. Another operator reported

cracked sealant and barrel nut corrosion

on an airplane having 20,655 total flight

hours and 4,768 total flight cycles. Of

the sixteen barrel nuts removed from

that airplane and inspected, several

were found to be corroded.

A recent report was received of four

cracked barrel nuts found on a Boeing

Model 767–300 series airplane; three of

those four were found on one side of the

airplane. This report revealed that the

issue was more urgent than initial

reports indicated. Subsequently, another

report was received from an operator of

a Group 1 airplane(Group 1 airplanes

were delivered with H–11 alloy steel

bolts and nuts), indicating that a broken

barrel nut was found and both the bolt

and the barrel nut were H–11 alloy steel

(no dissimilar metal). This report

revealed that the unsafe condition also

exists on Group 1 airplanes with H–11

alloy steel bolts installed.

Such conditions, if not corrected,

could result in reduced structural

integrity of the vertical fin attachment

joint, loss of the vertical fin, and

consequent loss of controllability of the

airplane.

Explanation of Relevant Service

Information

The FAA has reviewed and approved

Boeing Service Bulletin 767–53–0085,

dated May 14, 1998, and Boeing Alert

Service Bulletin 767–53A0085, Revision

1, dated July 1, 1999. The service

bulletins describe procedures for

repetitive internal and external visual

inspections to find discrepancies (i.e.,

cracked or damaged sealant, signs of

corrosion damage, cracked or broken

barrel nuts), of the barrel nuts that

attach the vertical fin to body section

48, and follow-on actions. The followon actions include, but are not limited

to, the following:

• Replacement of the barrel nut with

a new Inconel barrel nut if any

discrepancy is found at any barrel nut

location.

• A torque check on each attachment

bolt of the vertical fin if no discrepancy

is found at any barrel nut location.

• Replacement of the barrel nut with

a new Inconel barrel nut if a bolt can be

turned during the torque check.

• Repeat of the internal and external

visual inspections.

The service bulletins also provide an

optional replacement of all 16 H–11

steel alloy barrel nuts of the vertical fin

with Inconel barrel nuts, which would

eliminate the need for the repetitive

inspections.

Explanation of the Requirements of the

Rule

Since an unsafe condition has been

identified that is likely to exist or

develop on other products of this same

type design, the AD would require

accomplishment of the actions specified

in the service bulletin described

previously, except as discussed below.