FAA Issues AD on Lycoming Engines

^{Written by: Phil Lightstone
Image courtesy of flightlineweekly.com}

Recently, the FAA issued a new Airworthiness Directive (AD) for Lycoming Engines (Lycoming), project identifier AD-2023-00783-E and FAA Docket No. FAA-2024-1695. The AD targets certain Lycoming model engines that have a certain Connecting Rod Assembly and/or Connecting Rod Bushing.  The AD was created after several reports of connecting rod failures which resulted in inflight engine shut downs. The AD will become into effect on December 5, 2024 and will impact approximately 16,000 engines and the FAA estimates the cost of compliance to be $17,312,000 USD.

The AD has two parts: repetitive oi 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. A terminating action to the connecting rod bushings inspections requires the replacement of the bushings with parts eligible for installation.

Lycoming Service Bulletin 480F suggests changing the oil every 50 hours or every four months, whichever comes first. Several aircraft maintenance manuals specify oil replacement every 50 hours without a calendar time restriction. The AD does not define or mandate the frequency of oil changes after the initial oil change. The FAA’s AD states: “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.”

There are nine connecting rod bushings and assemblies in scope of the FAA’s AD with ship date ranges between 01/30/2009 and 02/14/2017. Part numbers include: LW-13923; LW11750; 78030; LW-19332; LW-13865; 77450; LW-13422; LW13937; and LW-15288. The impacted parts are installed on a large variety of Lycoming engines including the popular IO-360 series and IO540 series.

Mike Busch, Founder and CEO of Savvy Aviation (www.SavvyAviation.com) reports: “this AD is uncommonly light handed for the FAA allowing aircraft owners to perform the inspection work themselves. It appears that Lycoming had a bunch of bushings which were not dimensionally correct and could shift in the connecting rod, which could cause a fragment of bronze metal to break off and make its way to the oil screen. The nice thing about the AD, is that it does not require the engine cylinders to be removed unless bronze metal is seen in the oil screen.”

Mark van Berkel, President and CEO Canadian Owners and Pilots Association (COPA) reports: “while the AD is annoying it could be worse. As an aircraft owner, I am a big fan of doing the right amount of maintenance, ensuring that my next flight is not put at risk due to a maintenance induced issue. This AD provides a reasonable set of steps for those Lycoming engines with the suspected faulty parts installed.”

Details on the proposed AD can be found at www.regulations.gov/document/FAA-2024-1695-0001 and www.regulations.gov/document/FAA-2024-1695-0004. Do determine if your Lycoming engine is in scope to the AD, you might consider reviewing your aircraft’s Engine Technical Logbook to determine if the Lycoming components were installed in your aircraft based upon the date ranges. The specific part numbers and date ranges are listed in the AD document. As with all ADs, you should discuss the matter with your AME and AMO to obtain detailed guidance from a professional.