Document headings vary by document type but may contain the following:
See the Document Drafting Handbook for more details.
AGENCY:
Federal Aviation Administration (FAA), DOT.
ACTION:
Final rule.
SUMMARY:
The FAA is adopting a new airworthiness directive (AD) for Lycoming Engines (Lycoming) model engines that have a certain connecting rod assemblies installed. This AD was prompted by several reports of connecting rod failures, which resulted in uncontained engine failure and in-flight shutdowns (IFSDs). This AD requires repetitive oil inspections for bronze metal particulates and, if found, additional inspections of the connecting rod bushings for damage, proper fit, movement, and wear, and replacement if necessary. As terminating action to the connecting rod bushing inspections, this AD requires replacement of the connecting rod bushings with parts eligible for installation. The FAA is issuing this AD to address the unsafe condition on these products.
DATES:
This AD is effective December 5, 2024.
The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of December 5, 2024.
ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2024-1695; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this final rule, any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Material Incorporated by Reference:
- For Lycoming material identified in this AD, contact Lycoming Engines, 652 Oliver Street, Williamsport, PA 17701; phone: (800) 258-3279; website:lycoming.com/contact/knowledge-base/publications.
- You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 1200 District Avenue, Burlington, MA 01803. For information on the availability of this material at the FAA, call (817) 222-5110. It is also available atregulations.gov under Docket No. FAA-2024-1695.
FOR FURTHER INFORMATION CONTACT:
James Delisio, Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: (516) 228-7321; email: james.delisio@faa.gov.
SUPPLEMENTARY INFORMATION:
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to Lycoming model engines that have certain connecting rod assemblies installed. The NPRM published in the Federal Register on June 28, 2024 (89 FR 53911). The NPRM was prompted by several reports of connecting rod failures, which resulted in uncontained engine failure and IFSDs, and a manufacturer investigation where it was determined that affected connecting rod small end bushings may be installed on additional populations of Lycoming engines. The manufacturer also determined that degradation of the connecting rod small end bushings is detectable during oil change inspections. In the NPRM, the FAA proposed to require repetitive oil inspections for bronze metal particulates and, if found, additional inspections of the connecting rod bushings for damage ( e.g. deterioration, missing metal), proper fit, movement, and wear, and replacement if necessary. As terminating action to the connecting rod bushing inspections, the NPRM also proposed to require replacement of the connecting rod bushings with parts eligible for installation. The FAA is issuing this AD to address the unsafe condition on these products.
Discussion of Final Airworthiness Directive
Comments
The FAA received one comment from Aeroclub de Columbia. The following presents the comment received on the NPRM and the FAA's response to the comment.
Request To Clarify Scheduling of Inspections
Aeroclub de Columbia requested that the FAA confirm whether the recurrent inspections required by paragraph (g) of the proposed AD should also be scheduled monthly for aircraft in 14 CFR part 91 (non-commercial) operations. Aeroclub de Columbia noted that Lycoming Service Bulletin 480F suggests changing the oil every 50 hours or every 4 months, but several aircraft maintenance manuals specify oil replacement every 50 hours without a calendar time restriction.
To clarify, this AD does not define or mandate the frequency of oil changes after the initial oil change. Subsequent oil changes are part of the engine's regular maintenance program, therefore the recurring frequency is outside the scope of this AD. Although repetitive inspections are required during this regular maintenance interval, they are tied to the operator's oil change frequency and that frequency is not being defined by this AD. The FAA did not change this AD as a result of this comment.
Conclusion
The FAA reviewed the relevant data, considered any comments received, and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these products. Except for minor editorial changes, and any other changes described previously, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Lycoming Mandatory Service Bulletin No. 630A, dated June 13, 2017, which specifies procedures for inspection of the connecting rod bushings for damage, proper fit, movement, and wear. This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.
Costs of Compliance
The FAA estimates that this AD affects 16,000 engines installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this AD:
Estimated Costs
| Action | Labor cost | Parts cost | Cost per product | Cost on U.S. operators |
|---|---|---|---|---|
| Inspect oil | 2 work-hours × $85 per hour = $170 | $65 | $235 | $3,760,000 |
| Inspect connecting rod bushings | 1 work-hour × $85 per hour = $85 | 0 | 85 | 1,360,000 |
| Replace connecting rod bushings (per bushing) | 4.5 work-hours × $85 per hour = $382 | 380 | 762 | 12,192,000 |
Table 1 to Paragraph ( c )—Affected P/Ns
| P/N | Affected part | Ship date range |
|---|---|---|
| LW-13923 | Connecting Rod Bushing | 01/30/2009-11/17/2015 |
| LW-11750 | Connecting Rod Assembly | 01/30/2009-11/19/2015 |
| 78030 | Connecting Rod Assembly | 01/30/2009-03/31/2016 |
| LW-19332 | Connecting Rod Assembly | 01/30/2009-01/03/2016 |
| LW-13865 | Connecting Rod Assembly | 01/30/2009-02/14/2017 |
| 77450 | Connecting Rod Assembly | 01/30/2009-02/14/2017 |
| LW-13422 | Connecting Rod Assembly | 01/30/2009-02/14/2017 |
| LW-13937 | Connecting Rod Assembly | 01/30/2009-02/14/2017 |
| LW-15288 | Connecting Rod Assembly | 01/30/2009-02/14/2017 |