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; Amendment 39-9024; AD 91-25-08 R1]

Airworthiness Directives; Cessna Aircraft Company Models 421C and

425 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment revises Airworthiness Directive (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. This action provides 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 this

action. The actions specified by this AD are intended to prevent wing

failure caused by excessive wing spar cracking.

DATES: Effective November 4, 1994.

The incorporation by reference of certain publications listed in

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

of November 4, 1994.

ADDRESSES: Service information that applies to this AD may be obtained

from the Cessna Aircraft Company, Customer Services, P.O. Box 1521,

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

Federal Aviation Administration (FAA), Central Region, Office of the

Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City,

Missouri 64106; or at the Office of the Federal Register, 800 North

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

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: A proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) to include an AD that would apply

to certain Cessna Models 421C and 425 airplanes was published in the

Federal Register on April 20, 1994 (59 FR 18768). The action proposed

to revise AD 91-25-08 by maintaining the wing front spar upper cap

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 kits that

are included as an attachment to the above-referenced service

bulletins.

Interested persons have been afforded an opportunity to participate

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

the one comment received.

The commenter states that, although the proposal does not apply to

the serial number airplanes that the commenter owns, all 16 hi-lock

pins of each aft main landing gear support (part number 5122724-1 and

5122724-2) were found loose during an annual inspection. The commenter

believes that the above-referenced main landing gear supports are

located in the same general area as the area referenced in the

proposal, and that these areas share the same structural loads. For

these reasons, the commenter proposes expanding the rule to include an

inspection of these main landing gear supports as well as the wing

front spar upper caps. The FAA concurs that the referenced main landing

gear supports are in the same general area as the wing front spar upper

caps (between the main landing gear actuating cylinder attachment and

the front spar wing attach fittings); however, the two do not share the

same structural loads. The main landing gear supports incur loads from

the landing gear while the upper spar caps incur loads from the gear

retraction cylinder. This AD is written only to detect and correct wing

front spar upper cap cracking because the FAA identified this as an

unsafe condition that needed AD corrective action. The FAA will

evaluate service difficulty reports on the main landing gear supports,

and, if found necessary, will initiate applicable rulemaking at that

time. The AD is unchanged as a result of this comment.

After careful review of all available information including the

comment referenced above, the FAA has determined that air safety and

the public interest require the adoption of the rule as proposed except

for minor editorial corrections. The FAA has determined that these

minor corrections will not change the meaning of the AD nor add any

additional burden upon the public than was already proposed.

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

affected by this AD, that it will take approximately 3 workhours per

airplane to accomplish the required action, and that the average labor

rate is approximately $55 an hour. Based on these figures, the total

cost impact of the AD 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 Cessna Aircraft Company has informed the FAA that 67 SK421-142

(-1 or -2) or SK425-44 (-1 or -2) service kits have been sold, thus

reducing or terminating the inspections for the particular airplane

wing front spar upper cap that the kit is installed on. Repetitive

inspections are no longer required on the airplane if both wing front

spar upper caps have service kits incorporated, and these kits are

incorporated without cracks present. The FAA has no reasonably

available means of finding out how many inspection reductions (kit

incorporated with cracks) and how many inspection terminations (kit

incorporated without cracks) are involved, or how many airplanes

incorporated a left wing kit (-1) and a right wing kit (-2). With this

in mind, the FAA does not know exactly how much this reduces the cost

of the inspections and optional modification portion of this AD on U.S.

operators; however, the FAA would estimate this cost reduction at

around $125,000, thus reducing the optional modification portion of

this AD from a fleetwide cost impact of $2,154,410 to $2,029,410. This

estimate is based on taking the average workhour per wing of 26

workhours (2 wings = 52 workhours) times the average labor rate of $55

per hour plus the average cost of the different kits.

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 copy of the final evaluation prepared for this

action is contained 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, 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. 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:

91-25-08 R1 Cessna Aircraft Company: Amendment 39-9024; 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

Secs. 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.

(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) The inspections and modifications required by this AD shall

be done in accordance with ATTACHMENT TO SERVICE BULLETIN to Cessna

Service Bulletin CQB91-8R1, or the ACCOMPLISHMENT INSTRUCTIONS

attachment to Cessna Service Bulletin MEB91-7R1, as applicable. The

modification required by this AD shall be accomplished in accordance

with Cessna SERVICE KIT SK421-142, dated July 3, 1993, or Cessna

SERVICE KIT SK425-44, dated November 6, 1992, as applicable. 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 Cessna Aircraft Company, P.O. Box

7704, Wichita, Kansas 67277. Copies may be inspected at the FAA,

Central Region, Office of the Assistant Chief Counsel, Room 1558,

601 E. 12th Street, Kansas City, Missouri, or at the Office of the

Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC.

(h) This amendment (39-9024) revises AD 91-25-08, Amendment 39-

8109.

(i) This amendment (39-9024) becomes effective on November 4,

1994.

Issued in Kansas City, Missouri, on September 12, 1994.

Barry D. Clements,

Manager, Small Airplane Directorate, Aircraft Certification Service.

[FR Doc. 94-23078 Filed 9-16-94; 8:45 am]

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