Airworthiness Directives; Boeing Model 737-100 and -200 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-152-AD; Amendment 39-10102; AD 97-17-01]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 737-100 and -200 Series

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to all Boeing Model 737-100 and -200 series airplanes, that

requires replacement of certain outboard and inboard wheel halves with

improved wheel halves. This amendment also requires cleaning and

inspecting certain outboard and inboard wheel halves for corrosion,

missing paint in large areas, and cracks; and repair or replacement of

the wheel halves with serviceable wheel halves, if necessary. This

amendment is prompted by a review of the design of the flight control

systems on Model 737 series airplanes. The actions specified by this AD

are intended to prevent failure of the wheel flanges, which could

result in damage to the hydraulics systems, jammed flight controls,

loss of electrical power, or other combinations of failures; and

consequent reduced controllability of the airplane.

DATES: Effective September 16, 1997.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of September 16, 1997.

ADDRESSES: The service information referenced in this AD may be

obtained from Allied Signal Aerospace Company, Bendix Wheels and Brakes

Division, South Bend, Indiana 46624; and Bendix, Aircraft Brake and

Strut Division, 3520 Westmoor Street, South Bend, Indiana 46628-1373.

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: David Herron, Aerospace Engineer,

Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane

Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,

SW., Renton, Washington 98055-4056; telephone (425) 227-2672; fax (425)

227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) to include an airworthiness

directive (AD) that is applicable to all Boeing Model 737-100 and -200

series airplanes was published in the Federal Register as a

supplemental notice of proposed rulemaking (NPRM) on March 14, 1997 (62

FR 12123). That action proposed to require replacement of certain

outboard and inboard wheel halves with improved wheel halves. That

action also proposed to require cleaning and inspecting certain

outboard and inboard wheel halves for corrosion, missing paint in large

areas, and cracks; and repair or replacement of the wheel halves with

serviceable wheel halves, if necessary.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

Support for the Proposal

Two commenters support the proposed rule.

Request To Withdraw the Proposal

One commenter states that review of the design of the flight

control systems on Model 737 series airplanes occurred on a military

aircraft, yet military airplanes are often subjected to harsh operating

environments and possibly operate with a lower level of inspection than

is found in commercial aviation. The commenter states that the existing

inspection schedules and inspection techniques in accordance with the

latest manufacturer's recommendations are adequate to prevent an unsafe

condition. The FAA infers from these remarks that the commenter

requests the proposed supplemental NPRM be withdrawn.

The FAA does not concur with the request to withdraw the

supplemental NPRM.

The FAA did not propose rulemaking for the subject unsafe condition

based solely on a single event. The FAA review of available service

information and the close proximity to the wheels of certain types of

equipment were contributing factors in the FAA's finding of the subject

unsafe condition. Furthermore, the commenter did not provide any

evidence to support its statement that military airplanes may have a

lower level of inspection than is found in commercial aviation, nor did

the commenter provide any substantiation for the statement that

existing inspections schedules and techniques are adequate to prevent

an unsafe condition.

Request to Remove Certain Airplanes From Applicability

One commenter, an operator, stated that its airplanes are equipped

with BF Goodrich main wheels rather than Bendix wheels. The FAA infers

that the operator requests that its airplanes be removed from the

applicability of this rule.

The FAA concurs that airplanes equipped with other than Bendix

wheels are not subject to the requirements of this rule. Since the

applicability of this rule clearly states that it applies only to

airplanes equipped with Bendix wheels, the FAA finds that no change to

the final rule is necessary.

Request To Correct Serial Numbers of the Wheel Halves

One commenter, the wheel half manufacturer, requests that the

serial numbers of the inboard wheel halves be revised based on its

further research into the manufacturing records of the wheel halves.

The manufacturer advises that the revised serial numbers reflect the

elimination of certain serial numbers of the wheel halves that have

been ``beefed up;'' therefore, those certain serial numbers do not need

to be replaced. The manufacturer contends that the correction of the

serial numbers will provide an economic benefit to operators as the

pool of useable wheel

[[Page 43068]]

halves would potentially be increased by 179 for inboard halves and 236

for outboard halves. The wheel half manufacturer also states that it

has issued Allied Signal, Aircraft Landing Systems, Service Information

Letter (SIL) #619, dated February 26, 1997, that corrects the serial

numbers. Specifically, the commenter requests that:

Paragraph (a) of the proposal be revised to read ``* * *

with an inboard wheel half with serial number (S/N) B-5898 or lower, or

S/N H-1721 or lower; or with an outboard wheel half with S/N B-5898 or

lower, or S/N H-0863 or lower * * *''

Paragraph (b) of the proposal be revised to read ``* * *

with an inboard wheel half with S/N B-5898 or lower, or S/N H-1721 or

lower; or with an outboard wheel half with S/N B-5898 or lower, or S/N

H-0863 or lower * * *''

Paragraph (b)(1) of the proposal be revised to read ``* *

* and replace it with an inboard wheel half having part number (P/N)

2607046, S/N 5899 or greater, or S/N H-1722 or greater.''

Paragraph (b)(2) of the proposal be revised to read ``* *

* and replace it with an outboard wheel half having P/N 2607047, S/N B-

5899 or greater, or S/N H-0864 or greater.''

The FAA concurs with the revision of the serial numbers based on

the commenter's justification. The final rule has been revised as

suggested by the commenter.

Additionally, the FAA has added a new ``Note 2'' to this final rule

to reference the SIL discussed by the commenter as an additional source

of service information concerning appropriate wheel half serial

numbers.

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

increase the economic burden on any operator nor increase the scope of

the AD.

Cost Impact

There are approximately 634 Boeing Model 737-100 and -200 series

airplanes of the affected design in the worldwide fleet. The FAA

estimates that 241 airplanes of U.S. registry will be affected by this

AD.

The FAA estimates that it will take approximately 4 work hours per

airplane to accomplish the required replacement of wheel halves at an

average labor rate of $60 per work hour. Required parts will cost

approximately $20,212 per airplane. Based on these figures, the cost

impact of the required replacement on U.S. operators is estimated to be

$4,928,932, or $20,452 per airplane.

The FAA also estimates that it will take approximately 2 work hours

per airplane to accomplish the required cleaning and inspection at an

average labor rate of $60 per work hour. Based on these figures, the

cost impact of the required cleaning and inspection on U.S. operators

is estimated to be $28,920, or $120 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:

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 the following new

airworthiness directive:

97-17-01 Boeing: Amendment 39-10102. Docket 96-NM-152-AD.

Applicability: Model 737-100 and -200 series airplanes equipped

with Bendix main wheel assemblies having part number 2601571-1,

certificated in any category.

Note 1: This AD applies to each airplane 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 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 (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 the wheel flanges, which could result in

damage to the hydraulics systems, jammed flight controls, loss of

electrical power, or other combinations of failures and consequent

reduced controllability of the airplane, accomplish the following:

Note 2: Allied Signal, Aircraft Landing Systems, Service

Information Letter #619, dated February 26, 1997, is an additional

source of service information for appropriate wheel half serial

numbers.

(a) For airplanes equipped with a Bendix main wheel assembly

having part number (P/N) 2601571-1 with an inboard wheel half with

serial number (S/N) B-5898 or lower, or S/N H-1721 or lower; or with

an outboard wheel half with S/N B-5898 or lower, or S/N H-0863 or

lower; accomplish the following:

(1) Within 180 days after the effective date of this AD, and

thereafter at each tire change until the replacement required by

paragraph (b) of this AD is accomplished: Accomplish the actions

specified in paragraphs (a)(1)(i), (a)(1)(ii), and (a)(1)(iii) of

this AD, in accordance with the Accomplishment Instructions of

Allied Signal Service Bulletin No. 737-32-026, dated April 26, 1988.

(i) Clean any inboard and outboard wheel half specified in

paragraph (a) of this AD. And

(ii) Inspect the wheel halves for corrosion or missing paint. If

any corrosion is found, or if any paint is missing in large areas,

prior to further flight, strip or remove paint, and remove any

corrosion. And

[[Page 43069]]

(iii) Perform an eddy current inspection to detect cracks of the

bead seat area.

(2) If any cracking is found during the inspections required by

this paragraph, prior to further flight, repair or replace the wheel

halves with serviceable wheel halves in accordance with procedures

specified in the Component Maintenance Manual.

(b) For airplanes equipped with a Bendix main wheel assembly

having P/N 2601571-1 with an inboard wheel half with S/N B-5898 or

lower, or S/N H-1721 or lower; or with an outboard wheel half with

S/N B-5898 or lower, or S/N H-0863 or lower; accomplish the

following: Within 2 years after the effective date of this AD,

accomplish the actions specified in paragraphs (b)(1) and (b)(2) of

this AD, in accordance with Bendix Service Information Letter (SIL)

392, Revision 1, dated November 15, 1979. Accomplishment of the

replacement constitutes terminating action for the repetitive

inspections required by paragraph (a) of this AD.

(1) Remove any inboard wheel half specified in paragraph (b) of

this AD, and replace it with an inboard wheel half having P/N

2607046, S/N 5899 or greater, or S/N H-1722 or greater. And

(2) Remove any outboard wheel half specified in paragraph (b) of

this AD, and replace it with an outboard wheel half having P/N

2607047, S/N B-5899 or greater, or S/N H-0864 or greater.

(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, Seattle Aircraft Certification

Office (ACO), 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, Seattle ACO.

Note 3: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Seattle ACO.

(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) Certain actions shall be done in accordance with Bendix

Service Information Letter (SIL) 392, Revision 1, dated November 15,

1979. Certain other actions shall be done in accordance with Allied

Signal Service Bulletin No. 737-32-026, dated April 26, 1988. 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 Allied Signal Aerospace Company,

Aircraft Landing Systems, 3520 Westmoor Street, South Bend, Indiana

46628-1373. 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.

(f) This amendment becomes effective on September 16, 1997.

Issued in Renton, Washington, on August 4, 1997.

John J. Hickey,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 97-20952 Filed 8-11-97; 8:45 am]

BILLING CODE 4910-13-U