AD 95-03-03

This amendment adopts a new airworthiness directive (AD) that is applicable to Hartzell Propeller Inc. Model HC-B4TN-3/T10173F(N)(B,K)-12.5 and HC-B4TN-3A/T10173F(N)(B,K)- 12.5 propellers installed on Beech A100 and A100A aircraft. This action requires an initial and repetitive inspections, and specified rework or retirement, as necessary, of the propeller hub assemblies and propeller blades. This amendment is prompted by a determination that the current hub design and blade repair limits do not adequately protect against initiation of fatigue cracks in the propeller hub arm bore and do not prevent the resonant speed of the propeller from shifting into the permitted ground idle operating range. The actions specified in this AD are intended to prevent initiation of fatigue cracks in the propeller hub arm bore and subsequent progression to failure, with departure of the hub arm and blade, that may result in loss of aircraft control.

Final rule; request for comments.

95-03-03 Hartzell Propeller Inc.: Amendment 39-9140. Docket 95-ANE-06.
Applicability: Hartzell Propeller Inc. Model HC-B4TN-3/T10173F(N)(B,K)-12.5 and HC-B4TN- 3A/T10173F(N)(B,K)-12.5 propellers installed on Beech A100 and A100A aircraft. NOTE: The parentheses indicate the presence or absence of an additional letter(s) which vary the basic propeller blade model designation. This airworthiness directive (AD) still applies regardless of whether these letters are present or absent on the propeller blade model designation.

Compliance: Required as indicated, unless accomplished previously.

To prevent initiation of fatigue cracks in the propeller hub arm bore and subsequent progression to failure, with departure of the hub arm and blade, that may result in loss of aircraft control, accomplish the following:

(a) For affected propellers with Time-Since-New (TSN) greater than or equal to 3,000 hours or TSN unknown on the effective date of this AD, within the next 150 hours Time-In-Service (TIS) or the next 12 calendar months after the effective date of this AD, whichever occurs first, accomplish paragraphs (a)(1), (a)(2), and either (a)(3) or (a)(4) of this AD:

(1) Remove affected propeller hub and blade assemblies from the aircraft for inspection, and accomplish specified rework or retirement, if necessary, in accordance with Hartzell Propeller Inc. Alert Service Bulletin (ASB) No. A196A, dated December 27, 1994.

(2) Replace propeller blade assemblies that have been rejected or retired per paragraph (a)(1) of this AD with propeller blade assemblies inspected and reworked, if necessary, per paragraph (a)(1) of this AD or new blade assemblies. Thereafter, at intervals of 3,000 hours TIS or 60 calendar months, whichever occurs first, inspect, and rework or retire, if necessary, the blade assemblies in accordance with Hartzell Propeller Inc. ASB No. A196A, dated December 27, 1994.

(3) Replace propeller hub assemblies that have been rejected or retired per paragraph (a)(1) of this AD with propeller hub assemblies that have had the hub arm bores inspected (and reworked as necessary), pilot tubes replaced, and have a metal impression stamp at the end of the hub serial number with suffix letter "M", followed by a number (1, 2, 3, etc.) to indicate the number of repetitive inspections performed in accordance with Hartzell ASB No. A196A, dated December 27, 1994. Thereafter, at intervals of 600 hours TIS or 60 calendar months, whichever occurs first, inspect, and rework or retire, as necessary, the hub assemblies in accordance with Hartzell Propeller Inc. ASB No. A196A, dated December 27, 1994.

(4) Replace propeller hub unit Part Number (P/N) 840-139 or P/N 840-89, unless already accomplished, with a hub that has compressive rolled internal bearing bores, which is identified with the addition of a third letter "A" in the hub serial number prefix (e.g. "CDA1234"). Thereafter, at intervals of 3,000 hours TIS or 60calendar months, whichever occurs first, inspect, and rework or retire, as necessary, the hub assemblies in accordance with Hartzell Propeller Inc. ASB No. A196A, dated December 27, 1994.

(b) For affected propellers with less than 3,000 hours TSN on the effective date of this AD, within the next 300 hours TIS, or prior to the accumulation of 3,150 hours TSN, or within the next 12 calendar months after the effective date of this AD, whichever occurs first, accomplish paragraphs (a)(1), (a)(2), and either (a)(3) or (a)(4) of this AD.

(c) Any blade repairs made after the effective date of this AD shall be accomplished in accordance with the procedures specified in Hartzell ASB No. A196A, dated December 27, 1994.

(d) For propellers that experience a blade strike, as defined in paragraph (f) of this AD, after the effective date of this AD, prior to further flight, accomplish paragraphs (a)(1), (a)(2), and either (a)(3) or (a)(4) of this AD.

(e) For propellers that have experienced a blade strike, as defined in paragraph (f) of this AD, prior to the effective date of this AD, within the next 100 hours TIS after the effective date of this AD, accomplish paragraphs (a)(1), (a)(2), and either (a)(3) or (a)(4) of this AD.

(f) A blade strike is defined as a propeller having any blade(s) bent beyond the repair limits specified in Hartzell Propeller Inc. Standard Practices Manual 61-01-02, Revision 1, Pages 1104- 1105, dated June 1994.

(g) 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, Chicago Aircraft Certification Office. The request should be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Chicago 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 Chicago Aircraft Certification Office.

(h) Except when propellers have experienced a blade strike, 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.

(i) The inspections and rework shall be accomplished in accordance with the following service documents:

Document No.
Pages
Date
Hartzell Propeller Inc.
ASB No. A196A
1-5
December 27, 1994
Total pages: 5.

Hartzell Propeller Inc. Standard Practices Manual 61-01-02, Revision 1
1104-1105
June 1994
Total pages: 2.

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 Hartzell Propeller Inc., One Propeller Place, Piqua, OH 45356-2634; telephone (513) 778-4200, fax (513) 778-4391. Copies maybe 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.

(j) This amendment becomes effective on March 17, 1995.

On December 22, 1994, the Federal Aviation Administration (FAA) issued airworthiness directive (AD) 95-01-02, applicable to Hartzell Model HC-B4TN-5(D,G,J)L/LT10282(B,K)-5.3R and HC-B4TN-5(D,G,J)L/LT10282N(B,K)-5.3R propellers installed on Mitsubishi MU-2 series aircraft. That AD requires new propeller blade repair limits and requires replacement of propeller hubs with new improved fatigue strength steel hubs which require inspection, and specified rework as necessary, at a repetitive interval of 3,000 hours time in service (TIS). That AD was prompted by a determination that the previous hub design and blade repair limits did not adequately protect against initiation of fatigue cracks in the propeller hub arm bore and did not prevent the resonant speed of the propeller from shifting into the permitted ground idle operating range when installed in Mitsubishi MU-2 Series aircraft. That condition, if not corrected, can result in fatigue cracks in the propeller hub arm bore and subsequent progression to failure, with departure of the hub arm and blade, that may result in loss of aircraft control.

The FAA has determined, based on operating stresses and similarity of propeller type design, that similar fatigue cracks could occur in Hartzell Propeller Inc. Model HC-B4TN- 3/T10173F(N)(B,K)-12.5 and HC-B4TN-3A/T10173F(N)(B,K)-12.5 propellers installed on Beech A100 and A100A aircraft.

The FAA has reviewed and approved the technical contents of Hartzell Propeller Inc. Alert Service Bulletin (ASB) No. A196A, dated December 27, 1994, that describes procedures for initial and repetitive inspections, and specified rework or retirement, as necessary, of the propeller hub assemblies and propeller blades.

Since an unsafe condition has been identified that is likely to exist or develop on other Hartzell Propeller Inc. Model HC-B4TN-3/T10173F(N)(B,K)-12.5 and HC-B4TN-3A/T10173F(N)(B,K)- 12.5 propellers of the same type design, this AD isbeing issued to require initial and repetitive inspections, and specified rework or retirement, as necessary, of the propeller hub assemblies and propeller blades. The actions are required to be accomplished in accordance with the ASB 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 specifiedunder 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 95-ANE-06." 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 isdetermined 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 adding the following new airworthiness directive: