AD 96-19-05

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.

Final rule; request for comments.

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 thatthe 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, accomplishthe following:

(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 beadof 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 becomes effective on October 1, 1996.

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 numbers 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 clarifiedprocedures.

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 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 progressas 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'sideas 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.

Section 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: