AD 96-08-01 R1

On April 1, 1996, the Federal Aviation Administration (FAA) issued airworthiness directive (AD) 96-08-01, applicable to Hamilton Standard Model 14RF-9 propellers, which superseded priority letter AD 95-24-09, and requires an ultrasonic shear wave inspection for cracks or surface indications, a one-time visual and fluorescent penetrant inspection for mechanical damage, and repair of the propeller blade shank. That action was prompted by a report of an inflight loss of a Hamilton Standard Model 14RF-9 propeller blade installed on an Embraer EMB-120 aircraft. The loss of the propeller blade resulted in the subsequent loss of the propeller and portions of the gearbox. The propeller blade separated due to a crack approximately 9 inches from the butt end of the blade. The FAA determined that the crack initiated on the outer surface of the blade shank in an area of mechanical damage induced as a result of a localized interference condition between the bladespar and the foam mold which occurred during blade manufacture. That condition, if not corrected, could result in propeller blade separation due to propeller blade shank cracking, which could result in loss of control of the aircraft.

Since the issuance of that AD, the manufacturer has developed new inspection and repair procedures for mechanical damage (dents) greater than .005 inches deep to a maximum of .010 inches in depth. The new inspection and repair procedures will ensure that the structural integrity of the blades is maintained. Also, the new inspection and repair procedures will allow certain blades having dents greater than .005 inches deep that were removed from service in accordance with AD 96-08-01 to be inspected and repaired in accordance with Hamilton Standard Service Bulletin No. 14RF-9-61-105, dated July 24, 1996, and returned to service.

The new inspection procedure can find damage in areas of the propeller blade shank that might have been damaged by interference with the propeller blade foam mold during manufacture. The damage will be visible when the overlying fiberglass and adhesive layers are removed. Prior to returning damaged propeller blades to service, blades must be repaired in accordance with the applicable service or alert service bulletin.

The FAA has reviewed and approved the technical contents of Hamilton Standard Service Bulletin (SB) No. 14RF-9-61-86, Revision 4, and Alert Service Bulletin (ASB) No. 14RF-9-61-A90, both dated November 9, 1995, that describe procedures for an ultrasonic shear wave inspection of propeller blade shanks for cracks or surface indications; and Hamilton Standard ASB No. 14RF-9- 61-A92, Revision 2, dated March 6, 1996, that describes procedures for an inspection and repair for mechanical damage. In addition, the FAA has reviewed and approved the technical contents of Hamilton Standard SB No. 14RF-9-61-105, Original, dated July 24, 1996, which describes eddy current inspection and repairprocedures for those propeller blades with dents that exceed .005 inches deep to a maximum of .010 inches in depth.

Since an unsafe condition has been identified that is likely to exist or develop on other propellers of this same type design, this AD revises AD 96-08-01, by adding a new paragraph (d) which allows inspection and repair of propeller blades with mechanical damage greater than .005 inches deep to a maximum of .010 inches in depth in accordance with Hamilton Standard Service Bulletin No. 14RF-9-61-105, dated July 24, 1996. This revision will also enable those propellers that were removed from service in accordance with 96-08-01, and that are determined repairable in accordance with SB 14RF-9-61-105, to be returned to service.

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 energyaspects 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 96-ANE-04." 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 theauthority 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. 39.13 - [AMENDED] 2. Section 39.13 is revised to read as follows: