AD 95-05-03

This amendment supersedes an existing airworthiness directive (AD), applicable to Hamilton Standard 14RF series, 14SF series, and Hamilton Standard/British Aerospace 6/5500/F series propellers, that currently requires a one-time ultrasonic shear wave inspection for cracks in the propeller blade taper bore. This amendment requires initial and repetitive ultrasonic shear wave inspections, and a one-time visual and borescope inspection of the taper bore for corrosion as a terminating action to the ultrasonic shear wave inspections. This amendment is prompted by reports of two incidents where a portion of the propeller blade was lost in flight. The actions specified by this AD are intended to prevent loss of a propeller blade due to cracks initiating in the blade taper bore, that can result in possible aircraft damage, and possible loss of aircraft control.

Final rule; request for comments.

95-05-03 Hamilton Standard: Amendment 39-9170. Docket 95-ANE-02. Supersedes AD 94-09-06, Amendment 39-8894.

Applicability: Hamilton Standard Models 14RF-9, 14RF-19, 14RF-21, and 14SF-5, 14SF-7, 14SF-11, 14SFL11, 14SF-15, 14SF-17, 14SF-19, and 14SF-23; and Hamilton Standard/British Aerospace 6/5500/F propellers installed on but not limited to Embraer EMB-120 and EMB 120-RT; SAAB-SCANIA SF 340B; Aerospatiale ATR42-100, ATR42-300, ATR42-320, ATR72; DeHavilland DHC-8-100 series, DHC-8-300 Series; Construcciones Aeronauticas SA (CASA) CN-235 series and CN-235-100; Canadair CL-215T and CL-415; and British Aerospace ATP airplanes.

Compliance: Required as indicated, unless accomplished previously.

To prevent loss of a propeller blade due to cracks initiating in the blade taper bore, that can result in possible aircraft damage, and possible loss of aircraft control, accomplish the following:

(a) For propeller blades that have accumulated 1,750 or more flight cycles since ultrasonic shear wave inspection in accordance with AD 94-09-06, perform either paragraph (a) or (d) of this AD within 100 flight cycles of the effective date of this AD:

(1) Perform an ultrasonic shear wave inspection for cracks in the blade taper bore, in accordance with the procedures described in the following Hamilton Standard Alert Service Bulletins (ASB's), as applicable: No. 14RF-21-61-A53, dated April 18, 1994, and No. 14RF-21-61- A55, Revision 1, dated October 5, 1994; No. 14SF-61-A73, dated April 18, 1994, and No. 14SF-61- A74, Revision 1, dated October 5, 1994; No. 14RF-19-61-A34, dated April 18, 1994, and No. 14RF- 19-61-A36, Revision 1, dated October 5, 1994; No. 14RF-9-61-A66, dated April 18, 1994, and No. 14RF-9-61-A69, Revision 1, dated October 5, 1994; No. 6/5500/F-61-A27, dated April 18, 1994, and No. 6/5500/F-61-A29, dated August 29, 1994. Remove cracked propeller blades and replace with a serviceable blade prior to further flight.

(2) Thereafter, perform repetitive ultrasonic shear wave inspections at intervals not to exceed 1,250 CIS since last inspection in accordance with the applicable Hamilton Standard ASB's listed in paragraph (a)(1) of this airworthiness directive (AD). Remove cracked propeller blades and replace with a serviceable blade prior to further flight.

(3) No later than December 31, 1997, perform the visual and borescope inspection required by paragraph (d) of this AD.

(b) For propeller blades that have accumulated less than 1,750 flight cycles since ultrasonic shear wave inspection in accordance with AD 94-09-06, perform either paragraph (a) or (d) of this AD before accumulating 1,850 flight cycles since ultrasonic shear wave inspection in accordance with AD 94-09-06.

(c) For propeller blades that have not been inspected in accordance with AD 94-09-06, perform paragraphs (a)(1) or (d) of this AD prior to installing the blade in service and thereafter perform paragraph (a)(2) of this AD if applicable.

(d) Prior to December 31, 1997, remove and scrap the propeller inner taper bore cork seal and visually inspect the inside surface of the taper bore for corrosion pits in accordance with the applicable Hamilton Standard Service Bulletins (SB's): No. 14RF-9-61-70, dated August 26, 1994; No. 14RF-19-61-37, dated August 29, 1994; No. 14RF-21-61-56, dated August 29, 1994; No. 14SF- 61-75, dated August 29, 1994; and No. 6/5500/F-61-30, dated August 29, 1994.

(1) For propeller blades found with any corrosion pits, remove from service prior to further flight and send the propeller blades to an FAA-approved repair facility for disposition in accordance with Hamilton Standard ASB's No. 14SF-61-A74, Revision 1, dated October 5, 1994; No. 14RF-9-61-A69, Revision 1, dated October 5, 1994; No. 14RF-19-61-A36, Revision 1, dated October 5, 1994; No. 14RF-21-61-A55, Revision 1, dated October 5, 1994; and No. 6/5500/F-61-A29, dated August 29, 1994; as applicable.

(2) For propeller blades found with no corrosion pits, mark the blade and return it to service in accordance with the Hamilton Standard SB's listed in paragraph (d) of this AD.

(3) Returning propeller blades to service in accordance with paragraph (d) of this AD constitutes terminating action to the repetitive ultrasonic shear wave inspections required by paragraph (a)(2) of this AD.

(e) For the purpose of this AD, a flight cycle is defined as one takeoff and the next landing of an aircraft.

(f) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Boston Aircraft Certification Office. The request should be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Boston Aircraft Certification Office. NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Boston Aircraft Certification Office.

(g) 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 aircraft to a location where the requirements of this AD can be accomplished.

(h) The requirements of this AD shall be done in accordance with the following Hamilton Standard ASB's and SB's:

Document No.
Pages
Revision
Date
ASB No. 14SF-61-A74
1-7
1
October 5, 1994
Total pages: 7.

ASB No. 14SF-61-A73
1-19
Original
April 18, 1994
Total pages: 19.

SB No. 14SF-61-75
1-17
Original
August 29, 1994
Total pages: 17.

ASB No. 14RF-9-61-A69
1-6
1
October 5, 1994
Total pages: 6.

ASB No. 14RF-9-61-A66
1-19
Original
April 18, 1994
Total pages: 19.

SB No. 14RF-9-61-70
1-17
Original
August 29, 1994
Total pages: 17.

ASB No. 14RF-19-61-A36
1-6
1
October 5, 1994
Total pages: 6.

ASB No. 14RF-19-61-A34
1-19
Original
April 18, 1994
Total pages: 19.

SB No. 14RF-19-61-37
1-17
Original
August 29, 1994
Total pages: 17.

ASB No. 14RF-21-61-A55
1-6
1
October 5, 1994
Total pages: 6.

ASB No. 14RF-21-61-A53
1-19
Original
April 18, 1994
Total pages: 19.

SB No. 14RF-21-61-56
1-17
Original
August 29, 1994
Total pages: 17.

ASB No. 6/5500/F-61-A29
1-5
Original
August 29, 1994
Total pages: 5.

ASB No. 6/5500/F-61-A27
1-19
Original
April 18, 1994
Total pages: 19.

SB No. 6/5500/F-61-30
1-17
Original
August 29, 1994
Total pages: 17.

The incorporation by reference of the following Hamilton Standard ASB's was approved by the Director of the Federal Register as of May 2, 1994: ASB's No. 14RF-9-61-A66, No. 14RF-19-61-A34, No. 14RF-21-61-A53, No. 14SF-61-A73, and No. 6/5500/F-61-A27, all dated April 18, 1994. The incorporation by reference of all other Hamilton Standard ASB's and SB's listed in this AD 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 Hamilton Standard, One Hamilton Road, Windsor Locks, CT 06096-1010; telephone (203) 654-3610. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(i) This amendment becomes effective on March 23, 1995.

On April 18, 1994, the Federal Aviation Administration (FAA) issued airworthiness directive (AD) 94-09-06, Amendment 39-8894 (59 FR 19127, April 22, 1994), applicable to Hamilton Standard 14RF series, 14SF series, and Hamilton Standard/British Aerospace 6/5500/F series propellers, to require an ultrasonic shear wave inspection of the blade taper bore for cracks, and replacement, if necessary, with a serviceable propeller blade. That action was prompted by reports of two incidents where a portion of the propeller blade was lost in flight. On March 13, 1994, an ATR-42 commuter aircraft experienced an inflight loss of the right propeller and a portion of the associated engine gearbox. Later that month, on March 30, 1994, an Embraer EMB-120 commuter aircraft also experienced an inflight loss of a portion of a propeller blade. This blade fractured at approximately the 19 inch station and the remainder of the propeller blade, propeller, and gearbox remainedintact.

Subsequent metallurgical examination of these fractured blades revealed that the fracture initiated in a small cavity or pit that formed on the inner surface of the taper bore inside the aluminum blade spar. Further laboratory investigations revealed these corrosion pits may develop occasionally when chlorine residue present in the cork used to seal the inner taper bore combines with water in the presence of oxygen. That condition, if not corrected, could result in loss of a propeller blade due to cracks initiating in the blade taper bore, that can result in possible aircraft damage, and possible loss of aircraft control.

Since the issuance of that AD, the FAA has conducted engineering and laboratory investigation and analysis of world-wide inspection results received from AD 94-09-06. This data indicates that either periodic ultrasonic shear wave inspection of the propeller taper bore should be conducted every 1,250 flight cycles in service (CIS) in order to discover cracks that may initiate in pits, or a one-time visual and borescope inspection of the taper bore should be conducted after removing the propeller inner taper bore cork seal to insure that no corrosion has occurred.

The FAA has reviewed and approved the technical contents of the following Hamilton Standard Service Bulletins (SB's) and Alert Service Bulletins (ASB's):

ASB's No. 14RF-9-61-A66, No. 14RF-19-61-A34, No. 14RF-21-61-A53, No. 14SF-61-A73, and No. 6/5500/F-61-A27, all dated April 18, 1994, that describe procedures for ultrasonic shear wave inspections of the blade taper bores for cracks. These ASB's are the same as those referenced in AD 94-09-06.

SB's No. 14RF-9-61-70, dated August 26, 1994; No. 14RF-19-61-37, dated August 29, 1994; No. 14RF-21-61-56, dated August 29, 1994; No. 14SF-61-75, dated August 29, 1994; and No. 6/5500/F-61-30, dated August 29, 1994. These SB's describe procedures to remove the propeller inner taper bore cork seal and inspect the inside surface of the taper bore for corrosion pits visually and by borescope. Blades found to be free of pits are marked and reidentified. Propeller blade maintenance logs shall also be annotated to show compliance with this AD. Blades found to have any corrosion pits during these inspections shall be removed from service prior to further flight and sent to an FAA-approved repair facility for disposition in accordance with the instructions of the appropriate SB.

ASB's No. 14SF-61-A74, Revision 1, dated October 5, 1994; No. 14RF-9-61-A69, Revision 1, dated October 5, 1994; No. 14RF-19-61-A36, Revision 1, dated October 5, 1994; No. 14RF-21-61- A55, Revision 1, dated October 5, 1994; and No. 6/5500/F-61-A29, dated August 29, 1994. These ASB's list the serial numbers of all blades with unpeened taper bores by model that require inspection. These ASB's present several options as to how to inspect the blade taper bores, and also give instructions to operators and repair facilitieson how to report inspection data in order to show compliance with the AD.

Since an unsafe condition has been identified that is likely to exist or develop on other propellers of this same type design, this AD supersedes AD 94-09-06 to require initial and repetitive ultrasonic shear wave inspections and a one-time visual and borescope inspection of the taper bore for corrosion. Accomplishment of the visual and borescope inspection constitutes terminating action to the repetitive ultrasonic shear wave inspections. The actions are required to be accomplished in accordance with the SB's and ASB's described previously.

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public 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 under the caption "ADDRESSES." 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 andafter 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 95-ANE-02." The postcard will be date stamped and returned to the commenter.

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. A copy of it, if filed, may be obtained from 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. 39.13 - [AMENDED]
2. Section 39.13 is amended by removing Amendment 39-8894, (59 FR 19127, April 22, 1994), and by adding a new airworthiness directive, Amendment 39-9170, to read as follows: