Auburntsts
Well Known Member
Just got notification from the FAA:
drs.faa.gov
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New Lycoming AD for connecting rod assemblies
- Thread starter Auburntsts
- Start date
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.
I guess this mandates analysis of the oil specifically for bronze. It does not specify the part numbers of the affected connecting rod small end bushings, but does terminate the AD if you replace them.
I guess you could swap the connecting rod small end bushings without splitting the case
I guess this mandates analysis of the oil specifically for bronze. It does not specify the part numbers of the affected connecting rod small end bushings, but does terminate the AD if you replace them.
I guess you could swap the connecting rod small end bushings without splitting the case
| 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 |
Table 1 to Paragraph ( c )—Affected P/Ns
Similar to "X" means it was sold as Experimental, or to an Experimental builder/owner.
Pretty sure the answer is "yes".
Also, the rule does not mandate oil analysis for bronze. Only visual inspection of the oil filters and screen.
pazmanyflyer
Well Known Member
Larry, you bought that engine from Van's right? IIRC, the "Y" is Van's company designation for "experimental" working with Lycoming.
Sort of yes. I actually bought it from someone who bought it from Vans.
Thanks. That makes sense. I will add the AD to my manual and checklists.
AZSteve053
Well Known Member
The new AD references Lycoming Mandatory Service Bulletin No. 630A, dated June 13, 2017 however they do NOT reference Lycoming Mandatory Service Bulletin No. 632B, dated August 04, 2017 (WHY ?) which gives much more info on the issue, shows a special tool inspection/replacement and gives a definitive engine s/n table.
Appears to me the FAA is casting a very wide range of engines here... Just an observation.
Here's a phrase that could use more precision:
And if one does find a particulate or two, how can you identify it as coming from the rod bushings? Aren't there other bronze parts in the engine (I *thought* so, but I'm not an engine building expert, others could chime in here)? Or are the only bronze parts the rod end bushings?
ANY particles or particulates? Of any size? So a single tiny, barely-visible particle? What does this phrase mean, if anything? I'd expect more definite specs here.
And if one does find a particulate or two, how can you identify it as coming from the rod bushings? Aren't there other bronze parts in the engine (I *thought* so, but I'm not an engine building expert, others could chime in here)? Or are the only bronze parts the rod end bushings?
Auburntsts
Well Known Member
I’m gonna rely on my oil analysis as the primary indicator backed up by visual on the filter and screen, which is what I do anyway on all of my oil changes. I start to see a spike then I’m gonna call Barrett and get further advice.
skylor
Well Known Member
Oil analysis is not a substitute for cutting open and visually inspecting the oil filter and inspecting the sump "finger strainer". Gross failures produce particles too large to show up in the spectrographic oil analysis results!
Skylor
Auburntsts
Well Known Member
Never said it was. However I also believe in using all the tools available. It’s quite possible there will be a precursor rise in copper and tin before visible particles are present. IMO if you wait until you see particles that large you are danger close to a catastrophic failure. That said oil analysis is not a panacea but I think it’s an important part of a holistic approach to engine maintenance.
Anything caught in the finger strainer will be big enough to have a part number…lol
What I didn't get from any of the text was: what is the root cause of these failures? What's different about these bushings or their installation, or the rods, or something, that caused the failures they observed? Metallurgy? Dimensioning? Assembly method? Operations?
These are the rod P/Ns not the bushing part numbers he was asking about
One can only assume theses are OEM Lycoming small end bushings shipped with the above rods and applicable dates
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It appears from SBs that it's non-conforming small end bushings that are coming loose and working their way out and causing failures. My guess is it's a tolerance issue causing too loose a fit
Lycoming MSB 480F explains the limits and corrective action for bronze particles...size and quantity
The recent (last 10-15 years) has been to “design in” quality (one time cost) and not inspect for quality (re-occurring cost). I have always thought this would end up bitting you in the end.
Poor quality most often has a huge effect on bottom line as it will certainly show itself eventually in sales, reputation, and possibly liability. The current daily aviation news cycle is proving that out for at least one aviation company.
Don't get too spun up. Not to overstate the obvious, but we should be inspecting filters and screens for metals at every oil change anyway. For an individual maintaining his own, as most of us are, the compliance requirements are not a big deal.
That said, if you are selling your airplane, do not change the oil and filter. However good your intentions may be, it generates a red flag discussion between the purchaser and his pre-purchase mechanic.
That said, if you are selling your airplane, do not change the oil and filter. However good your intentions may be, it generates a red flag discussion between the purchaser and his pre-purchase mechanic.
What happens when you need to change your oil and filter? Like if you fly your plane?
It generates a caveat in the report. Facts are facts; the inspector cannot make a judgement regarding this AD when the filter is fresh.
Y is for experimental
So in other words you cannot fly your plane once the oil times out?
skylor
Well Known Member
I think most people sell their planes because the aren't flying them enough...
If a sale is eminent, why not save the media and post inspection remnants to show a potential new owners mechanic.
Or, state you did the inspection and found nothing, which should be logged anyway.
Chris, it's your choice. I'm just sayin' a seller is not always doing himself a favor by presenting an airplane with a fresh oil and filter.
Makes sense.
However, if I was selling an airplane I was flying and it needed an oil change it would get it. If by chance a prospective buyer showed up right after, and became uncomfortable that they couldn’t directly check it themselves, I would tell them “this airplane isn’t for you”, and move on.
In a prior thread, a poster was inquiring about Titan engines, which may have Lycoming parts with similar connecting rod numbers to those in the AD. My Titan IO-370 lists the connecting rod number as AEL 11750-S; the Lycoming AD part number is LW 11750. I emailed JB at Titan to get a clarification and the following is his response as of today..."The AEL 11750-S rods are not affected by the AD that affects certain Lycoming connecting rods that are part number LW 11750. The Continental rod bushing number is AEL 13923. Continental AEL 11750-S connecting rods and bushings are manufactured by Continental, not Lycoming, have different part numbers, and therefore not affected."Just got notification from the FAA:
Dynamic Regulatory System
I assume that this clarifies the AD as it relates to Titan engines. Steve
Do you have JB's current email? Tks Barry
I got an email from JB "No Lycoming connecting rods have ever been used in Titan engines." ; so this AD does not apply to Titan Engines. Cheers Barry
Well that is a relief! I am flying behind a Titan IO360 with close to 1200 relatively trouble-free hours. That said, I cut the filter and check the strainer at every oil filter change.
Note...when Blackstone (and any other spectro analysis lab) says "microscopic", they are talking about particles less than 15 microns in size. The industry generally considers 10 microns as the upper detection limit for ICP spectro, unless larger particles are first dissolved with an acid procedure.
