Airworthiness Directives: Cessna Aircraft Company Models 421C and 425 Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 91-CE-83-AD]

Airworthiness Directives: Cessna Aircraft Company Models 421C and

425 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to revise AD 91-25-08, which currently

requires repetitively inspecting both wing front spar upper caps for

cracks on certain Cessna Aircraft Company (Cessna) Models 421C and 425

airplanes, and repairing cracks that exceed certain limits. The

proposed action would provide the option of incorporating a certain

wing spar upper cap service kit as either terminating action or as an

extension to the repetitive inspections currently required. Wing front

spar upper cap cracks at the main landing gear actuating cylinder

attachment fitting on three of the affected airplanes prompted the

proposed action. The actions specified by the proposed AD are intended

to prevent wing failure caused by excessive wing spar cracking.

DATES: Comments must be received on or before June 30, 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-83-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 the Cessna Aircraft Company, Customer Services, P.O. Box 1521,

Wichita, Kansas 67201. This information also may be examined at the

Rules Docket at the address above.

FOR FURTHER INFORMATION CONTACT: Mr. Larry Abbott, Aerospace Engineer,

FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Room

100, Wichita, Kansas 67209; telephone (316) 946-4123; facsimile (316)

946-4407.

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-83-AD.'' 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-83-AD, room 1558, 601 E. 12th Street,

Kansas City, Missouri 64106.

Discussion

AD 91-25-08, Amendment 39-8109 (56 FR 60056, November 27, 1991),

currently requires repetitively inspecting both wing front spar upper

caps for cracks on certain Cessna Models 421C and 425 airplanes, and

repairing any crack found that exceeds certain limits. The action is

accomplished in accordance with the instructions in Cessna Service

Bulletin (SB) MEB91-7 or SB CQB91-8, both dated October 18, 1991, as

applicable.

Since issuance of AD 91-25-08, Cessna has developed certain wing

front spar upper cap service kits. The FAA has determined that these

service kits, if incorporated, would either eliminate the need or

extend the time necessary for the currently required repetitive

inspections.

Cessna has revised both SB MEB91-7 and SB CQB91-8 to include

reference of the service kits mentioned above. Cessna has also issued

attachments to these service bulletins that specify procedures for

incorporating the service kits.

After examining the circumstances and reviewing all available

information related to the proposed action, the FAA has determined

that: (1) The repetitive inspections can be either eliminated or

extended (depending on whether cracks are found) if the service kits

referenced above are incorporated; and (2) AD action should be taken to

prevent wing failure because of excessive wing spar cracking.

Since an unsafe condition has been identified that is likely to

exist or develop in other Cessna Models 421C and 425 airplanes of the

same type design, the proposed AD would revise AD 91-25-08 by

maintaining the repetitive inspection and possible crack repair

requirement, and adding the option of incorporating the applicable

Cessna service kits to either eliminate or extend the inspection time

interval (depending on whether cracks are found) of the repetitive

inspections. The proposed inspections would be accomplished in

accordance with the Accomplishment Instructions section of Attachment

to Service Bulletin (SB) to Cessna SB CQB91-8R1, or the Accomplishment

Instructions attachment to Cessna SB MEB91-7R1, as applicable. The

proposed inspection-extending or inspection-terminating modifications

(optional) would be accomplished in accordance with the instructions to

the applicable service kit that are included as an attachment to the

above-referenced service bulletins.

The FAA estimates that 551 airplanes in the U.S. registry would be

affected by the proposed AD, that it would take approximately 3

workhours per airplane to accomplish the proposed inspection, and that

the average labor rate is approximately $55 an hour. Based on these

figures, the total cost impact of the proposed inspection on U.S.

operators is estimated to be $90,915. This figure does not take into

account the cost of repetitive inspections nor the cost of the optional

inspection-extending or inspection-terminating service kit

installations. The FAA has no way of determining how many repetitive

inspections each operator would incur over the lifetime of the

airplane.

In addition, the FAA estimates 52 workhours to install service kits

on the spar caps at an average labor rate of approximately $55 an hour,

and $1,050 cost per airplane for service kit parts. Based on these

figures, the cost for the optional service kit installations on U.S.

operators would be $2,154,410 or $3,910 per airplane. After

incorporation of these kits, the repetitive inspections would be

terminated or the number of repetitive inspections would be reduced

depending on whether the spar was cracked.

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 91-25-08, Amendment 39-

8109 (56 FR 60056, November 27, 1991), and by adding a new

airworthiness directive to read as follows:

Cessna Aircraft Company: Docket No. 91-CE-83-AD; Revises AD 91-25-

08, Amendment 39-8109.

Applicability: The following model and serial number airplanes,

certificated in any category:

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Model Serial Nos.

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421C............................... 421C0801 through 421C1807.

425................................ 425-0002 through 425-0236.

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Compliance: Required initially upon the accumulation of 3,000

hours time-in-service (TIS) or within the next 50 hours TIS after

the effective date of this AD, whichever occurs later, unless

already accomplished within the last 300 hours TIS, and thereafter

as indicated in the body of this AD.

Note 1: The compliance times specified in this AD take

precedence over those referenced in the applicable service

information.

To prevent wing failure caused by excessive wing spar cracking,

accomplish the following:

(a) Fluorescent penetrant inspect both the left and right wing

front spar upper caps for cracks between the main landing gear

actuating cylinder attachment and the front spar wing attach

fittings in accordance with the Accomplishment Instructions section

of Attachment to Service Bulletin (SB) to Cessna SB CQB91-8R1, or

the Accomplishment Instructions attachment to Cessna SB MEB91-7R1,

as applicable.

(b) If any crack is found that is parallel (inboard-outboard) to

the top of the spar cap, install the applicable SK421-142 or SK425-

44 service kit (-1 for left spar cap and -2 for right spar cap) in

accordance with instructions to the applicable service kit (included

with the service bulletins referenced in paragraph (a) of this AD)

at the times that correspond with the following crack lengths, and

reinspect (as applicable) as specified in paragraph (d) of this AD:

(1) If equal to or less than 2.0 inches in length, within the

next 200 hours TIS;

(2) If more than 2.0 inches and less than 2.5 inches in length,

within the next 50 hours TIS; or

(3) If 2.5 or more inches in length, prior to further flight.

(c) If any crack (regardless of length) is found that is not

parallel (inboard-outboard) to the top of the spar cap, prior to

further flight, obtain a repair scheme from the manufacturer through

the Wichita Aircraft Certification Office (ACO), incorporate this

repair scheme, and reinspect as specified in paragraph (d) of this

AD.

(d) Reinspect (fluorescent penetrant) the left and right wing

front spar upper caps for cracks in accordance with those procedures

specified in paragraph (a) of this AD at intervals presented within

the applicable criteria below:

(1) With cracks less than or equal to 2.0 inches in length that

are parallel (inboard-outboard) to the top of the spar cap, at 50-

hour TIS intervals until the applicable service kit is installed in

accordance with paragraph (b) of this AD, and then reinspect

thereafter at intervals not to exceed 600 hours TIS.

(2) With cracks found and the applicable SK421-142 or SK425-44

service kit (-1 for left spar cap and -2 for right spar cap)

incorporated, at 600-hour TIS intervals.

(3) With no cracks found and the applicable SK421-142 or SK425-

44 service kit (-1 for left spar cap and -2 for right spar cap) not

incorporated, at 300-hour TIS intervals; or

(4) With no cracks found and the applicable SK421-142 or SK425-

44 service kit (-1 for left spar cap and -2 for right spar cap)

incorporated, no repetitive inspections required.

(e) 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.

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

compliance time that provides an equivalent level of safety may be

approved by the Manager, Wichita ACO, 1801 Airport Road, room 100,

Mid-Continent Airport, Wichita, Kansas 67209. The request shall be

forwarded through an appropriate FAA Maintenance Inspector, who may

add comments and then send it to the Manager, Wichita ACO.

Note 2: Information concerning the existence of approved

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

obtained from the Wichita ACO.

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

the document referred to herein upon request to the Cessna Aircraft

Company, P.O. Box 7704, Wichita, Kansas 67277; 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.

(h) This amendment revises AD 91-25-08, Amendment 39-8109.

Issued in Kansas City, Missouri, on April 14, 1994.

Barry D. Clements,

Manager, Small Airplane Directorate, Aircraft Certification Service.

[FR Doc. 94-9473 Filed 4-19-94; 8:45 am]

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