The Federal Aviation Administration (FAA) has received reports of two incidents where the incident aircraft lost a portion of a propeller blade inflight. Investigation revealed the presence of cracks initiating on the inside of the propeller blade taper bore that led to fracture of the propeller blade. In one incident, the fractured propeller blade penetrated the aircraft fuselage, entering a passenger seat and causing decompression. This condition, if not corrected, could result in loss of the propeller blade due to cracks initiating in the blade taper bore, that can result in possible aircraft damage, and possible loss of aircraft control.
The FAA has reviewed and approved the technical contents of Hamilton Standard Alert Service Bulletin (ASB) No. 14RF-9-61-A66, No. 14RF-19-61-A34, 14RF-21-61-A53, 14SF-61-A73 and 6/5500/F-61-A27, all dated April 18, 1994, that describe procedures for a ultrasonic shear wave inspection of the blade taper bore for cracks.
Since an unsafe condition has been identified that is likely to exist or develop on other propellers of the same type design, this airworthiness directive (AD) is being issued to prevent loss of the propeller blade due to cracks initiating in the blade taper bore, that can result in possible aircraft damage, and possible loss of aircraft control. This AD requires an ultrasonic shear wave inspection of the blade taper bore for cracks, and replacement, if necessary, with a serviceable propeller blade. Operators must perform this inspection within 45 days after the effective date of this AD. The FAA has determined that the affected propellers must be inspected in as short a time period as possible to provide an acceptable level of safety. In addition, the FAA has determined that 45 days provides that level of safety considering available logistical support and replacement propeller blades. The investigation into these failures continues, and the FAA may consider further rulemaking based on future findings. Propellers with cracks must be replaced prior to further flight. The actions are required to be accomplished in accordance with the 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 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 94-ANE-15." 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 14 CFR part 39 of the Federal Aviation Regulations 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 adding the following new airworthiness directive: