Airworthiness Directives; Fairchild Aircraft SA226 and SA227 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-CE-10-AD; Amendment 39-9753; AD 96-19-05]

RIN 2120-AA64

Airworthiness Directives; Fairchild Aircraft SA226 and SA227

Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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[[Page 48067]]

SUMMARY: This amendment supersedes Airworthiness Directive (AD) 95-19-

07, which currently requires the following on Fairchild Aircraft SA226

and SA227 series airplanes equipped with certain main landing gear

(MLG) and nose landing gear (NLG): repetitively inspecting, using

ultrasonic methods, the left-hand and right-hand MLG yokes and the NLG

yokes for stress corrosion cracking, and, if any cracked yokes are

found that exceed certain limits, replacing either the cracked yoke,

the yoke/cylinder combination, or the affected MLG or NLG assembly.

This action also supersedes priority letter AD 95-19-07 R1, which was

issued to incorporate revised service information. Reports of landing

gear failures on the affected airplanes prompted the original AD

action. This action requires the same inspections, but requires

replacing any MLG and NLG assembly with any cracks instead of allowing

flight until certain crack limits are exceeded. The inability to

determine or predict crack growth on areas where stress corrosion

occurs on primary structure with a single-load path (MLG and NLG

assemblies are considered such structure) prompted this action. The

actions specified by this AD are intended to prevent MLG or NLG failure

caused by stress corrosion cracking in the yokes, which could result in

loss of control of the airplane during landing operations.

DATES: Effective October 1, 1996.

The incorporation by reference of certain publications listed in

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

of October 1, 1996.

Comments for inclusion in the Rules Docket must be received on or

before November 7, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Counsel, Attention: Rules Docket No. 96-CE-10-AD, Room 1558, 601 E.

12th Street, Kansas City, Missouri 64106.

Service information that applies to this AD may be obtained from

Fairchild Aircraft, P.O. Box 790490, San Antonio, Texas 78279-0490;

telephone (210) 824-9421. This information may also be examined at the

FAA, Central Region, Office of the Assistant Chief Counsel, Attention:

Rules Docket 96-CE-10-AD, 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. Hung Viet Nguyen, Aerospace

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

Fort Worth, Texas 76193-0150; telephone (817) 222-5155; facsimile (817)

222-5960.

SUPPLEMENTARY INFORMATION:

Events Leading to the Issuance of AD 95-19-07

Several reports of main landing gear (MLG) and nose landing gear

(NLG) failure on Fairchild Aircraft SA226 and SA227 series airplanes

prompted the FAA to issue Airworthiness Directive (AD) 95-19-07,

Amendment 39-9369 (60 FR 47687, September 14, 1995). AD 95-19-07

required the following on Fairchild Aircraft SA226 and SA227 series

airplanes equipped with certain MLG and NLG: repetitively inspecting,

using ultrasonic methods, the left-hand and right-hand MLG yokes and

the NLG yokes for stress corrosion cracking, and, if any cracked yokes

are found that exceed certain limits, replacing either the cracked

yoke, the yoke/cylinder combination, or the affected MLG or NLG

assembly. Accomplishment of the inspections required by AD 95-19-07 was

required in accordance with Fairchild Service Bulletin (SB) 226-32-065,

Fairchild SB 227-32-039, or Fairchild SB CC7-32-007, all Issued: August

16, 1995, as applicable.

The airplanes in the above-referenced incidents are equipped with

at least one part number (P/N) OAS5453 MLG assembly and P/N OAS5451 NLG

assembly. Metallurgical analysis of the yokes of the right-hand and

left-hand MLG assemblies and NLG assemblies on several of these

airplanes revealed that the failure was initiated by stress corrosion

cracking of the yokes.

Explanation of the Relevant Service Information

The service bulletins incorporated into AD 95-19-07 contain some

incorrect procedures that could prevent an owner/operator from

correctly accomplishing the actions required by that AD. For this

reason, Fairchild Aircraft revised SB 226-32-065, SB 227-32-039, and SB

CC7-32-007, each of which incorporates the following effective pages

and revision levels:

------------------------------------------------------------------------

Effective pages SB date

------------------------------------------------------------------------

1, 5, and 8............................... Revised: September 28, 1995.

2, 3, 4, 6, 7, and 9...................... Issued: August 16, 1995.

------------------------------------------------------------------------

These service bulletins specify improved procedures for ultrasonically

inspecting the left-hand and right-hand Ozone Industries, Inc. MLG yoke

(reference: MLG assembly P/N OAS5453, all dash numbers up to and

including -19), and Ozone Industries, Inc. NLG yoke (reference: NLG

assembly P/N OAS5451, all dash number up to and including -17), on

Fairchild Aircraft SA226 and SA227 series airplanes.

The Need to Revise AD 95-19-07

The FAA determined that the revised service information should be

incorporated into AD 95-19-07 to allow for proper inspection of the MLG

and NLG yokes of the affected airplanes, and issued priority letter AD

95-19-07 R1 to prevent MLG or NLG failure caused by stress corrosion

cracks in the yokes, which could result in loss of control of the

airplane during landing operations. The priority letter revised AD 95-

19-07 by (1) retaining the repetitive inspections and possible

replacement required by AD 95-19-07; and (2) incorporating the revised

service bulletins to require accomplishment of the actions in

accordance with corrected and clarified procedures.

Reason for This Action

After in-depth analysis, the FAA has established a policy to not

allow airplane operation when known cracks exist in primary structure

(MLG and NLG assemblies are considered such structure). The FAA makes

allowances on this policy to account for parts availability provided

analysis shows that an interim, acceptable level of safety can be

maintained through a short-term, repetitive inspection program.

For this reason, the FAA has determined that the crack limits in

priority letter AD 95-19-07 R1 and AD 95-19-07, Amendment 39-9369,

should be eliminated and that AD action should be taken to require

immediate replacement of any cracked MLG or NLG assembly. Because

analysis shows that a repetitive inspection program can provide an

interim acceptable level of safety, the FAA will allow a grace period

for those owners/operators with airplanes where a crack is found in the

MLG or NLG yoke during the initial inspection required by this action.

Explanation of the Provisions of This AD

Since an unsafe condition has been identified that is likely to

exist or develop in other Fairchild Aircraft SA226 and SA227 series

airplanes of the same type design, this AD supersedes both priority

letter AD 95-19-07 R1 and AD 95-19-07, Amendment 39-9369, with a new AD

that retains the requirement of repetitively inspecting, using

ultrasonic methods, the left-hand and right-hand MLG yokes and the NLG

yokes for stress corrosion cracking, and

[[Page 48068]]

requires replacing either the cracked yoke, the yoke/cylinder

combination, or the affected MLG or NLG assembly, if any crack is

found. Accomplishment of the required inspections is in accordance with

Fairchild SB 226-32-065, Fairchild SB 227-32-039, or Fairchild SB CC7-

32-007, as applicable. Each of these service bulletins incorporates the

following effective pages and revision levels:

------------------------------------------------------------------------

Effective pages SB date

------------------------------------------------------------------------

1, 5, and 8............................... Revised: September 28, 1995.

2, 3, 4, 6, 7, and 9...................... Issued: August 16, 1995.

------------------------------------------------------------------------

Accomplishment of the replacement is in accordance with the applicable

maintenance manual.

Since a situation exists (possible loss of control of the airplane

during landing operations) that requires the immediate adoption of this

regulation, it is found that notice and opportunity for public prior

comment hereon are impracticable, and that good cause exists for making

this amendment effective in less than 30 days.

Compliance Time Criteria

The compliance time of this AD is presented in both calendar time

and hours time-in-service (TIS). Cracking of certain MLG yokes and NLG

yokes on the affected airplanes is caused by stress corrosion, which

starts as a result of high local stress (in the area where the piston

was shrink fitted to the yoke) incurred through operation. Corrosion

can then develop regardless of whether the airplane is in flight or on

the ground. The cracks may not be noticed initially as a result of the

stress loads, but could then progress as a result of corrosion. The

stress incurred during flight operations or temperature changes could

then cause rapid crack growth. In order to ensure that these stress

corrosion cracks do not go undetected, a compliance time of specific

hours TIS and calendar time (whichever occurs first) is utilized.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting immediate flight safety and, thus, was not

preceded by notice and opportunity to 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 above. 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, 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

AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their 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. 96-CE-10-AD.'' The postcard will be date stamped and

returned to the commenter.

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.

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and 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 (otherwise, an evaluation is

not required). A copy of it, if filed, may be obtained from the Rules

Docket.

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 USC 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing Airworthiness Directive

(AD) 95-19-07, Amendment 39-9369 (60 FR 47687, September 14, 1995), and

by adding a new AD to read as follows:

96-19-05 Fairchild Aircraft: Amendment 39-9753, Docket No. 96-CE-

10-AD. Supersedes both AD 95-19-07, Amendment 39-9369, and priority

letter AD 95-19-07 R1.

Applicability: Models SA226-T, SA226-AT, SA226-TC, SA226-T(B),

SA227-AC, SA227-AT, SA227-BC, SA227-TT, SA227-CC, and SA227-DC

airplanes (all serial numbers), certificated in any category, that

are equipped with one or more of the following:

1. Ozone Industries, Inc. main landing gear (MLG) yoke

(reference: MLG assembly part number OAS5453, all dash numbers up to

and including -19); or

2. Ozone Industries, Inc. nose landing gear (NLG) yoke

(reference: NLG assembly part number OAS5451, all dash numbers up to

and including -17).

Note 1: This AD applies to each airplane identified in the

preceding applicability provision, regardless of whether it has been

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 (g) 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 initially as follows and thereafter

as indicated in the body of this AD:

1. Within the next 100 hours time-in-service (TIS) after the

effective date of this AD or within the next 3 months after the

effective date of this AD, whichever occurs first; and

2. Upon the installation of one of the affected MLG or NLG

assemblies or yokes.

To prevent MLG or NLG failure caused by stress corrosion cracks

in the yokes, which could result in loss of control of the airplane

during landing operations, accomplish the following:

[[Page 48069]]

(a) Inspect, using ultrasonic methods, both sides of the left-

hand and right-hand MLG and NLG yokes for stress corrosion cracking

in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of

Fairchild Service Bulletin (SB) 226-32-065, Fairchild SB 227-32-039,

or Fairchild SB CC7-32-007, as applicable. Each of these service

bulletins incorporates the following effective pages and revision

levels:

------------------------------------------------------------------------

Effective pages SB date

------------------------------------------------------------------------

1, 5, and 8............................... Revised: September 28, 1995.

2, 3, 4, 6, 7, and 9...................... Issued: August 16, 1995.

------------------------------------------------------------------------

(b) If no cracks are found during the initial inspection

required by paragraph (a) of this AD, accomplish the following:

(1) Prior to further flight after the initial inspection

required by this AD, clean the MLG and NLG yoke and piston in

accordance with FIGURE 2 of the service bulletins referenced in this

AD, unless already accomplished;

(2) Prior to further flight after the initial inspection

required by this AD, apply a small bead of Products Research and

Chemical Corporation PR-1422 or PR-1435 sealant to the MLG and NLG

yoke as shown in FIGURE 2 of the service bulletins referenced in

this AD, and as described in the SA226/227 Series Service Repair

Manual, Chapter 51-30-03, Standard Practices--Sealing, unless

already accomplished; and

(3) Reinspect the MLG and NLG yokes at intervals not to exceed

2,500 hours TIS or 12 months, whichever occurs first, provided no

cracks are found. If cracks are found, prior to further flight,

replace the cracked part with a new or serviceable part in

accordance with the applicable maintenance manual, and accomplish

the cleaning of and sealant application to the MLG and NLG yoke and

piston as specified in paragraphs (b)(1) and (b)(2) of this AD. The

replacement may be accomplished by replacing the cracked yoke, the

total gear assembly, or the yoke/cylinder combination.

(c) If a crack is found during the initial inspection of this

AD, replace the cracked part with a new or serviceable part in

accordance with the applicable maintenance manual, and accomplish

the cleaning of and sealant application to the MLG and NLG yoke and

piston as specified in paragraphs (b)(1) and (b)(2) of this AD. The

replacement may be accomplished by replacing the cracked yoke, the

total gear assembly, or the yoke/cylinder combination. Replace any

cracked part in accordance with the following schedule:

(1) With a crack found with a length more than 1.5 inches in

length: PRIOR TO FURTHER FLIGHT;

(2) With a crack found with a length more than 1 inch but not

more than 1.5 inches: WITHIN THE NEXT 300 HOURS TIS AFTER THE

INITIAL INSPECTION REQUIRED BY THIS AD OR WITHIN THE NEXT 60 DAYS

AFTER THE INITIAL INSPECTION REQUIRED BY THIS AD, WHICHEVER OCCURS

FIRST;

(3) With a crack found with a length more than .75 inch but not

more than 1 inch: WITHIN THE NEXT 400 HOURS TIS AFTER THE INITIAL

INSPECTION REQUIRED BY THIS AD OR WITHIN THE NEXT 80 DAYS AFTER THE

INITIAL INSPECTION REQUIRED BY THIS AD, WHICHEVER OCCURS FIRST;

(4) With a crack found with a length more than .50 inch but not

more than .75 inch: WITHIN THE NEXT 500 HOURS TIS AFTER THE INITIAL

INSPECTION REQUIRED BY THIS AD OR WITHIN THE NEXT 100 DAYS AFTER THE

INITIAL INSPECTION REQUIRED BY THIS AD, WHICHEVER OCCURS FIRST; and

(5) With a crack found with a length less than 0.50 inch: WITHIN

THE NEXT 600 HOURS TIS AFTER THE INITIAL INSPECTION REQUIRED BY THIS

AD OR WITHIN THE NEXT 120 DAYS AFTER THE INITIAL INSPECTION REQUIRED

BY THIS AD, WHICHEVER OCCURS FIRST.

(d) Replacing a MLG or NLG yoke with either Ozone Industries,

Inc. MLG yoke (reference: MLG assembly part number OAS5453, all dash

numbers up to and including--19), or Ozone Industries, Inc. NLG yoke

(reference: NLG assembly part number OAS5451, all dash numbers up to

and including--17) re-establishes the effectivity of this AD.

(1) Repetitive inspections are required upon installation and at

intervals not to exceed 2,500 hours TIS or 12 months, whichever

occurs first, provided no cracks are found.

(2) If cracks are found, prior to further flight, replace the

cracked part with a new or serviceable part in accordance with the

applicable maintenance manual, and accomplish the cleaning of and

sealant application to the MLG and NLG yoke and piston as specified

in paragraphs (b)(1) and (b)(2) of this AD. The replacement may be

accomplished by replacing the cracked yoke, the total gear assembly,

or the yoke/cylinder combination.

(3) The crack limit replacement compliance times specified in

paragraph (c) of this AD only apply when cracks are found during the

initial inspection required by this AD. If any crack of any length

is found during a subsequent (any repetitive) inspection, the part

must be replaced PRIOR TO FURTHER FLIGHT.

(e) The MLG and NLG yokes to which this AD applies are

manufactured by Ozone Industries, Inc. Replacing these yokes with

approved parts, other than the following Ozone Industries, Inc. MLG

and NLG yokes eliminates the repetitive inspection requirements of

this AD:

(1) Ozone Industries, Inc. MLG yoke (reference: MLG assembly

part number OAS5453, all dash numbers up to and including--19).

(2) Ozone Industries, Inc. NLG yoke (reference: NLG assembly

part number OAS5451, all dash numbers up to and including--17).

(f) 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.

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

compliance time that provides an equivalent level of safety may be

approved by the Manager, Airplane Certification Office (ACO), FAA,

2601 Meacham Boulevard, Fort Worth, Texas 76193-0150. 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. Alternative methods of compliance approved in accordance with

either priority letter AD 95-19-07 R1 or AD 95-19-07, Amendment 39-

9369 (both superseded by this action), are not considered approved

as alternative methods of compliance with this AD.

Note 2: Information concerning the existence of approved

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

obtained from the Fort Worth ACO.

(h) The inspections required by this AD shall be done in

accordance with Fairchild Service Bulletin 226-32-065, Fairchild

Service Bulletin 227-32-039, or Fairchild Service Bulletin CC7-32-

007, as applicable. Each of these service bulletins incorporates the

following effective pages and revision levels:

------------------------------------------------------------------------

Effective pages SB date

------------------------------------------------------------------------

1, 5, and 8............................... Revised: September 28, 1995.

2, 3, 4, 6, 7, and 9...................... Issued: August 16, 1995.

------------------------------------------------------------------------

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 Fairchild Aircraft, P.O. Box 790490,

San Antonio, Texas 78279-0490. 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.

(i) This amendment (39-9753) supersedes AD 95-19-07, Amendment

39-9369, and priority letter AD 95-19-07 R1.

(j) This amendment (39-9753)1 becomes effective on October 1,

1996.

Issued in Kansas City, Missouri, on September 3, 1996.

Henry A. Armstrong,

Acting Manager, Small Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 96-22951 Filed 9-11-96; 8:45 am]

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