Airworthiness Directives: Fairchild Aircraft Models SA227-AC and SA227-AT Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 91-CE-12-AD]

Airworthiness Directives: Fairchild Aircraft Models SA227-AC and

SA227-AT Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to supersede Airworthiness Directive

(AD) 83-12-01, which currently requires repetitively inspecting the

lower wing skin panel for cracks on certain Fairchild Models SA227-AC

and SA227-AT airplanes, and installing wing skin reinforcement doublers

if any wing skin crack is found. The Federal Aviation Administration's

policy on aging commuter-class aircraft is to eliminate or, in certain

instances, reduce the number of certain repetitive short-interval

inspections when improved parts or modifications are available. The

proposed action would require installing wing skin reinforcement

doublers or wing skin stringer ties as terminating action for the

repetitive inspections that are currently required by AD 83-12-01. The

actions specified in the proposed AD are intended to prevent fatigue

failure of the lower wing skin panels, which could result in loss of

control of the airplane.

DATES: Comments must be received on or before June 10, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Central Region, Office of the Assistant Chief

Counsel, Attention: Rules Docket No. 91-CE-12-AD, Room 1558, 601 E.

12th Street, Kansas City, Missouri 64106. Comments may be inspected at

this location between 8 a.m. and 4 p.m., Monday through Friday,

holidays excepted.

Service information that applies to the proposed AD may be obtained

from Fairchild Aircraft, P.O. Box 790490, San Antonio, Texas 78279-

0490; telephone (210) 824-9421. This information also may be examined

at the Rules Docket at the address above.

FOR FURTHER INFORMATION CONTACT: Mr. Hung Viet Nguyen, Aerospace

Engineer, FAA, Airplane Certification Office, 2601 Meacham Boulevard,

Fort Worth, Texas 76137-0150; telephone (817) 222-5150; facsimile (817)

222-5959.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the

proposed 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 above. All

communications received on or before the closing date for comments,

specified above, will be considered before taking action on the

proposed rule. The proposals contained in this notice may be changed in

light of the comments received.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the proposed 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 proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket No. 91-CE-12AD.'' The postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request

to the FAA, Central Region, Office of the Assistant Chief Counsel,

Attention: Rules Docket No. 91-CE-12-AD, Room 1558, 601 E. 12th Street,

Kansas City, Missouri 64106.

Discussion

The FAA has determined that reliance on critical repetitive

inspections on aging commuter-class airplanes carries an unnecessary

safety risk when a design change exists that could eliminate or, in

certain instances, reduce the number of those critical inspections. In

determining what inspections are critical, the FAA considers (1) the

safety consequences of the airplane if the known problem is not

detected by the inspection; (2) the reliability of the inspection such

as the probability of not detecting the known problem; (3) whether the

inspection area is difficult to access; and (4) the possibility of

damage to an adjacent structure as a result of the problem.

These factors have led the FAA to establish an aging commuter-class

aircraft policy that requires incorporating a known design change when

it could replace a critical repetitive inspection. With this policy in

mind, the FAA recently conducted a review of existing ADs that apply to

Fairchild SA227 series airplanes. Assisting the FAA in this review were

(1) Fairchild Aircraft; (2) the Regional Airlines Association (RAA);

and (3) several operators of the affected airplanes.

From this review, the FAA has identified AD 83-12-01, Amendment

39-4693, as one that should be superseded with a new AD that would

require a modification that could eliminate the need for short-interval

and critical repetitive inspections. AD 83-12-01 currently requires

repetitively inspecting the lower wing skin panel for cracks on certain

Fairchild Models SA227-AC and SA227-AT airplanes, and installing wing

skin reinforcement doublers if any wing skin crack is found.

Fairchild has issued Service Bulletin (SB) No. 227-57-002, Issued:

June 6, 1983, Revised: January 23, 1984, which specifies procedures for

accomplishing the following on Models SA227-AC and SA227-AT airplanes:

dye penetrant inspections of the wing skin panel, and installation of

wing skin reinforcement doublers and wing skin stringer ties.

Based on its aging commuter-class aircraft policy and after

reviewing all available information, the FAA has determined that AD

action should be taken to eliminate the repetitive short-interval

inspections required by AD 83-12-01, and to prevent fatigue failure of

the lower wing skin panels, which could result in loss of control of

the airplane.

Since an unsafe condition has been identified that is likely to

exist or develop in other Fairchild Models SA227-AC and SA227-AT

airplanes of the same type design, the proposed AD would supersede AD

83-12-01 with a new AD that would (1) retain the requirement of

repetitively inspecting the lower wing skin panel, and installing wing

skin reinforcement doublers if any wing skin crack is found; and (2)

require either installing wing skin reinforcement doublers or wing skin

stringer ties as terminating action for the repetitive inspections. The

proposed actions would be accomplished in accordance with Fairchild SB

No. 227-57-002, Issued: June 6, 1983, Revised: January 23, 1984.

The FAA estimates that 125 airplanes in the U.S. registry would be

affected by the proposed AD, that it would take approximately 9

workhours per airplane to accomplish the proposed action if

reinforcement doublers were installed (1 workhour/inspection and 8

workhours/modification) or 25 workhours per airplane to accomplish the

proposed action if wing skin stringer ties were installed (1 workhour/

inspection and 24 workhours/modification), and that the average labor

rate is approximately $55 an hour. Parts cost approximately $56 per

airplane for the wing skin reinforcement doublers and $179 per airplane

for the wing skin stringer ties. Based on these figures, the total cost

impact of the proposed AD on U.S. operators is estimated to be either

$68,875 for those airplane operators incorporating the reinforcement

doubler modification or $194,250 for those airplane operators utilizing

the wing skin stringer ties modification. This cost figure is based on

the assumption that no affected airplane owner/operator has

accomplished one of the proposed inspection-terminating modifications.

The figure does not include repetitive inspection costs. The FAA has no

way of determining how many repetitive inspections each owner/operator

may incur.

The intent of the FAA's aging commuter airplane program is to

ensure safe operation of commuter-class airplanes that are in

commercial service without adversely impacting private operators. Of

the approximately 125 airplanes in the U.S. registry that would be

affected by the proposed AD, approximately 76 are operated in scheduled

passenger service. A significant number of the remaining 49 airplanes

are operated in other forms of air transportation such as air cargo and

air taxi.

The proposed AD allows 500 hours time-in-service (TIS) before

mandatory accomplishment of the design modification. The average

utilization of the fleet for those airplanes in commercial commuter

service is approximately 25 to 50 hours TIS per week. Based on these

figures, operators of commuter-class airplanes involved in commercial

operation would have to accomplish the proposed modification within 2

to 5 calendar months after the proposed AD would become effective. For

private owners, who typically operate between 100 to 200 hours TIS per

year, this would allow 2 to 5 calendar years before the proposed

modification would be mandatory.

The regulations proposed herein would 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

proposal would 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) if promulgated,

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 copy of the draft regulatory evaluation

prepared for this action has been placed in the Rules Docket. A copy of

it may be obtained by contacting 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.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration proposes to amend 14

CFR part 39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [AMENDED]

2. Section 39.13 is amended by removing AD 83-12-01, Amendment 39-

4693, and adding the following new AD to read as follows:

Fairchild Aircraft: Docket No. 91-CE-12-AD. Supersedes AD 83-12-01,

Amendment 39-4693.

Applicability: The following model and serial number airplanes,

certificated in any category:

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Model Serial No.

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SA227-AC........ 415, 416, and 420 through 554.

SA227-AT........ 423 through 554.

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Compliance: Required as indicated, unless already accomplished.

To prevent fatigue failure of the lower wing skin panels, which

could result in loss of control of the airplane, accomplish the

following:

(a) Within the next 50 hours time-in-service (TIS) after the

effective date of this AD, unless already accomplished (compliance

with AD 83-12-01), dye penetrant inspect the lower wing skin panel

in the area of Fuselage Station (FS) 187.0 in accordance with

paragraph IIA of the ACCOMPLISHMENT INSTRUCTIONS section of

Fairchild Service Bulletin (SB) 227-57-002, Issued: June 6, 1983,

Revised: January 23, 1984.

(1) If cracks are found, prior to further flight, install

reinforcement doublers, part number 27K31013-001 LH and 27K31013-002

RH, in accordance with paragraph IIB of the ACCOMPLISHMENT

INSTRUCTIONS section of Fairchild SB 227-57-002, Issued: June 6,

1983, Revised: January 23, 1984.

(2) If no cracks are found, reinspect thereafter at intervals

not to exceed 50 hours TIS until the modification specified in

paragraph (b) of this AD is accomplished.

(b) Within the next 500 hours TIS after the effective date of

this AD, unless already accomplished as specified in either

paragraph (a)(1) of this AD, accomplish one of the following:

(1) Install reinforcement doublers, part number 27K31013-001 LH

and 27K31013-002 RH, in accordance with paragraph IIB of the

ACCOMPLISHMENT INSTRUCTIONS section of Fairchild SB 227-57-002,

Issued: June 6, 1983, Revised: January 23, 1984; or

(2) Install stringer ties, P/N 27-13869, in accordance with

paragraph IIC of the ACCOMPLISHMENT INSTRUCTIONS section of

Fairchild SB 227-57-002, Issued: June 6, 1983, Revised: January 23,

1984.

(c) Incorporating the modification specified in paragraphs

(a)(1) and (b)(1) or (b)(2) of this AD terminates the repetitive

inspection requirement of this AD.

(d) Special flight permits may be issued in accordance with 14

CFR 21.197 and 21.199 to operate the airplane to a location where

the requirements of this AD can be accomplished.

(e) An alternative method of compliance or adjustment of the

initial or repetitive compliance times that provides an equivalent

level of safety may be approved by the Manager, Airplane

Certification Office (ACO), 2601 Meacham Boulevard, Fort Worth,

Texas 76137-0150. The request shall be forwarded through an

appropriate FAA Maintenance Inspector, who may add comments and then

send it to the Manager, Fort Worth ACO.

Note: Information concerning the existence of approved

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

obtained from the Fort Worth ACO.

(f) All persons affected by this directive may obtain copies of

the document referred to herein upon request to Fairchild Aircraft,

P.O. Box 790490, San Antonio, Texas 78279-0490; or may examine this

document at the FAA, Central Region, Office of the Assistant Chief

Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

(g) This amendment supersedes AD 83-12-01, Amendment 39-4693.

Issued in Kansas City, Missouri, on March 24, 1994.

Bobby W. Sexton,

Acting Manager, Small Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-7497 Filed 3-29-94; 8:45 am]

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