On March 7, 1986, the FAA issued AD 86-06- 02, Amendment 39-5259 (51 FR 10613, March 28, 1986). That AD requires initial and repetitive torque check inspections on the attach bolts on certain model Hartzell HC-B5MP-3 five bladed propellers installed on Aerospatiale (Nord) Model 262A airplanes modified by Supplemental Type Certificate (STC) SA2369SW, and Short Brothers Ltd. Model SD3-30 airplanes. Some SD3-30 airplanes are military surplus C23-A Sherpas airplanes. That AD was the result of investigations that revealed fretting wear between the engine and propeller mating flanges. The fretting wear results in loss of attach bolt preload, causing failure of the attach bolts. That condition, if not corrected, could result in propeller separation from the airplane.
Actions Since AD 86-06-02 Was Issued
Since February 2004, we received four reports of failed propeller attach bolts, part number (P/N) B-3339:
In February 2004, an operator reported a cracked Hartzell propeller attach bolt. The operator discarded the bolt and we could not perform a metallurgical investigation on the bolt.
In June of 2004, another operator reported two broken propeller attach bolts. Both bolts were examined and one was selected for metallurgical investigation. This bolt was found to meet type design.
In September of 2004, the Milwaukee Flight Standards District Office informed us that they received an operator's report of seven cracked or failed propeller attach bolts. All seven bolts were installed on the same propeller, and were found after a pilot reported problems with engine controls. We contacted Hartzell for assistance in investigating the bolt failure. The propeller hub and engine flange are being investigated for fretting, flatness, and thread damage.
In late September of 2004, during the review of the maintenance history of one of the above propellers, we found a fourth event of a cracked propeller attach bolt.
Relevant ServiceInformation
We have reviewed and approved the technical contents of Hartzell Alert Service Bulletin (ASB) A203A, dated January 5, 1995, that describes procedures for performing initial and repetitive inspections of attach bolts and if necessary, visual inspections of propeller mounting flanges.
Differences Between This AD and the Service Information
Although Hartzell ASB A203A, dated January 5, 1995, requires an initial torque check inspection within the next 100 hours TIS from the effective date of the original bulletin (dated September 2, 1994) for Short Brothers Ltd. Model SD3-30 airplanes, this AD requires an initial torque check inspection before further flight for SD3-30 airplanes. Also, although that ASB requires an initial torque check inspection within the next 120 hours TIS from the effective date of the original bulletin (September 2, 1994) for Aerospatiale (Nord) Model 262A airplanes, this AD requires an initial torque check inspection within 100 hours TIS for 262A airplanes.
FAA's Determination and Requirements of This AD
The unsafe condition described previously is likely to exist or develop on other Model HC-B5MP-3( )/M10282A( )+6 five bladed propellers of the same type design installed on Aerospatiale (Nord) Model 262A airplanes modified by STC SA2369SW, and Short Brothers Ltd. Model SD3- 30 airplanes. We are issuing this AD to prevent propeller separation from the airplane. This AD requires the following:
Before further flight, performing an initial torque check inspection of the propeller attach bolts on Short Brothers Ltd. Model SD3-30 airplanes unless already done within the last 120 hours TIS before the effective date of this AD; and
Repetitive torque check inspections of the propeller attach bolts within 120 hours TIS from the last inspection.
Within 100 hours TIS after the effective date of this AD, performing an initial torque check inspection of the propeller attach bolts on Aerospatiale (Nord) Model 262A airplanes; and
Repetitive torque check inspections of the propeller attach bolts within 100 hours TIS from the last inspection.
If the bolts fail the torque check, then visually inspect threads in hub bolt holes, and replace attach bolts and hub if necessary.
You must use the service information described previously to perform the actions required by this AD.
FAA's Determination of the Effective Date
Since an unsafe condition exists that requires the immediate adoption of this AD, we have found that notice and opportunity for public comment before issuing this AD are impracticable, and that good cause exists for making this amendment effective in less than 30 days.
Interim Action
These actions are interim actions and we may take further rulemaking actions in the future.
Comments Invited
This AD is a final rule that involves requirements affecting flight safety and was not preceded by notice and an opportunity for public comment; however, weinvite you to submit any written relevant data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include "AD Docket No. 86-ANE-7" in the subject line of your comments. If you want us to acknowledge receipt of your mailed comments, send us a self-addressed, stamped postcard with the docket number written on it; we will date-stamp your postcard and mail it back to you. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify it. If a person contacts us verbally, and that contact relates to a substantive part of this AD, we will summarize the contact and place the summary in the docket. We will consider all comments received by the closing date and may amend the AD in light of those comments.
We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications with you. You may get more information about plain language at http://www.faa.gov/language and http://www.plainlanguage.gov/.
Examining the AD Docket
You may examine the AD Docket (including any comments and service information), by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. See ADDRESSES for the location.
Regulatory Findings
We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect 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.
For the reasons discussed above, I certify that the regulation:
1. Is not a "significant regulatory action" under Executive Order 12866;
2. Is not a "significant rule" under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and
3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
We prepared a summary of the costs to comply with this AD and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include "AD Docket No. 86-ANE-7" in your request.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, under 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. 106(g), 40113, 44701.
Sec. 39.13[Amended]
2. The FAA amends Sec. 39.13 by removing Amendment 39-5259 (51 FR 10613, March 28, 1986), and by adding a new airworthiness directive, Amendment 39-13822, to read as follows: