Starting engine for fuel - but not flying? (Corrosion concerns)

[CorrosionConcern]

Posting this here to avoid being a lesson learned for the future.

I know this might be a bit of a stretch and most of what I’ve read online likely isn’t factual, but is there any concern of corrosion by taxiing the airplane to the fuel pit and then taxiing back to the hangar without flying? I’m wondering if this would be considered a ground run, which I absolutely try to avoid. I should say that I have plans to fly later in the day, but not right after fueling.

Are there any corrosion concerns by starting the airplane, taxiing, fueling and then taxiing right back to the hangar and putting the airplane away? Should I wait to fuel until right before my flight?

 

[AKBill]

I have no problem with taxing to a fuel pump and flying later that day. Once the engine comes to temp, any water generated during the short taxi will dissipate.

 

[Dan Thomas]

No problem. It takes time for the water that accumulates in the case to react with the oil and form the acids that do the real corroding. Yes, water will rust stuff, but it has to get past the oil film first. It's the acids that really get the engine's guts.

Water acts as an electrolyte. Put several different metals together with water and you get electron movement. Add oil, which contains a lot of different elements, and we get acids. Somewhere I read that nitric, sulfuric and hydrochloric acids are most likely.

 

[Skyrys62]

No problem. It takes time for the water that accumulates in the case to react with the oil and form the acids that do the real corroding.

Any idea on the amount of time?
I ask, because sometimes I want to taxi to the fuel pump, then put the plane away until the next morning being ready to leave early...or maybe even 2 days depending on schedule.

 

[455 Bravo Uniform]

I wouldn’t worry about it. You’re not ground running for years or each winter storage season.

Think about when maintenance shops ground run an engine pre or post repair. It’ll sit in the shop for days or weeks during diagnosis or repair, or after the repair before the owner flies it next.

I wouldn’t make a habit of it.

 

[danhagan]

I refuel after flight ... also, a mechanic recommended after shutdown to pull the oil stick back an inch or three and watch the steam that exits from the dipstick tube ... that steam that escapes has water and helps, but there's still going to be some after shutdown ...

 

[Kristin]

The ground run concern is really for inactive aircraft. Folks that take it out and run it for 10m every month or two and don't fly for years on the ones doing the damage. If the plane is flown regularly, it is not a concern.

 

[Checkout_my_Six]

Meh....you're over thinking this. Regular starting just to taxi....thinking I'll get everything lubed....is a problem. If it flys regularly this isn't an issue.

 

[kgruber]

In the early 1960s, Kenmore Air Harbor used to offer a service to their customers who parked in their lot. Once every couple of weeks, they would start their engines and let them run for 1/2 hour. All those engines turned into a pile of rust......so they stopped doing that.

 

[bbchien]

To the OP: you'll never get the oil hot enough to boil off the moisture in the oil. NOT A GOOD SCENARIO.

 

[Sac Arrow]

Most mechanics and engineers will agree that starting an engine without letting it come to full operating temperature plus 30 minutes to boil the moisture out of the oil (@bbchien, you're right, it's not temperature that boils the moisture off, but it is time) is a horrible practice to do for your engine. Obviously, in our cars on short trips that isn't possible, but usually short trips are interspersed with long trips. Short trip engines have a shorter life that long trip engines.

The biggest problem is that the sulfides present in the combustion byproducts react with the water in the oil from internal condensate, and bam, you have sulfuric acid. Very corrosive. You get a lot of condensate on startup of a cold engine, since water (steam) is a byproduct of combustion. It will condense and run off in to the oil sump until your engine is hot enough that it won't stick to the internal metal components as condensate.

So just leave it alone. If it is going to be a few months, taxi around and do some full power runups maybe once in the stretch. If it is going to be more than a few months, consider winterizing your engine.

 

[DFH65]

As was said you are WAY overthinking it.

 

[Dan Thomas]

So just leave it alone. If it is going to be a few months, taxi around and do some full power runups maybe once in the stretch.

Don't even do that. I've been into engines that sat for years and they were fine, if the last flight had been long enough and it was put away hot. There is no amount of taxiing around or runups that will get the oil hot enough to clean the case out. The CHTs will get way too hot first.

Yeah. WInterizing. If it's going to be a few months, drain the oil and put storage oil in it. Best to fly it for a bit on that, then fog the cylinders through the plug holes, put it away and not run it at all. https://www.shell.com/business-cust...centre/technical-talk/techart09-30071425.html

 

[Ed Haywood]

Any idea on the amount of time?

I think Lycoming guidance is to follow the storage procedure if an engine will sit more that 30 days. I seriously doubt anyone follows that, but for a period of inactivity of several months I would want to do it. Especially after seeing what the camshaft on my Decathlon looked like after sitting for several years with the previous owner. Eye opening, isn't it?

 

[Dan Thomas]

I think Lycoming guidance is to follow the storage procedure if an engine will sit more that 30 days. I seriously doubt anyone follows that, but for a period of inactivity of several months I would want to do it. Especially after seeing what the camshaft on my Decathlon looked like after sitting for several years with the previous owner. Eye opening, isn't it?

View attachment 108584 View attachment 108585 View attachment 108586 View attachment 108587

I'd be willing to bet that the previous owner had been ground-running it. That practice is far too common.

 

[Gary Ward]

I am surprised that I see this on my field, a plane ground run without flying it. I know of at least 2 at my field that this is done.
My 172 was flown 9 hrs in 10 years before I started flying it for friend who lost his medical. That is why he was not flying it along with 3 other planes he had.
I was really nervous about flying it for him because of how long it sat.
Turned out that is was ok after I flew it for about 400 hrs. He told me that he kept turning it over the engine with the propeller in his hangar.

It had 1400 hrs on it since new in 1980 when I started flying it 2018. I flew it for 400 hrs and then I removed the lifters first and they looked ok, some corrosion but no spauling. Then I removed all 4 clys and got a good look at the cam and it looked ok with microscopic rust pits in the lobes but no spauling. I put it back together and flew it another 100 hrs, so I know it was ok and would have flown another 500-1000 hrs. It had 1900 hrs when I replaced it. Only reason I replaced it is because like a dumbazz I ordered a replacement and had to get the old back as a core.
So I have to assume turning the motor over is better than actually starting it up without flying it?

 

[Dan Thomas]

So I have to assume turning the motor over is better than actually starting it up without flying it?

Turning it does no good. It will not pump any more oil at hand-crank speeds, and the rings just scrape off what oil might have been on the cylinder walls. Oil in the bearing/journal interfaces gets squeezed out. The highly-loaded cam/lifter interfaces get no lube at all. Since so much wear occurs right at startup until the oil pressure rises and starts feeding everything, I don't know why people simulate exactly that scenario by turning it over.

 

[Gary Ward]

Turning it does no good. It will not pump any more oil at hand-crank speeds, and the rings just scrape off what oil might have been on the cylinder walls. Oil in the bearing/journal interfaces gets squeezed out. The highly-loaded cam/lifter interfaces get no lube at all. Since so much wear occurs right at startup until the oil pressure rises and starts feeding everything, I don't know why people simulate exactly that scenario by turning it over.

Yes I agree with your thinking, I don't know how much he turned it over or if he even did. Just repeating what he told me one day. I think my late buddy and I got lucky that it survived after sitting for so long.
This an actual picture of me taxing it on his drag strip to take off. That is him in the pickup truck ahead of me leading me down the strip to turn around and take off. My heart was pounding. He wanted me out of there ASAP as it was minutes before the strip was to open. They put the xmas tree up right after I taxied by the beginning of the dragstrip. I stayed overhead of the strip for about an 1/2 hour making sure it kept running. It never quit running.
I flew it to a nearby airport where he rented a hangar so I could fly it for him and not have to get in and out of the dragstrip with it.

 

[Rgbeard]

Yes I agree with your thinking, I don't know how much he turned it over or if he even did. Just repeating what he told me one day. I think I and my late buddy got lucky that it survived after sitting for so long.
This an actual picture of me taxing it on his drag strip to take off. That is him in the pickup truck ahead of me leading me down the strip to turn around and take off. My heart was pounding. He wanted me out of there ASAP as it was minutes before the dragstrip was to open. They put the xmas tree up right after I taxied by the beginning of the dragstrip. I stayed overhead of the dragstrip for about an 1/2 hour making sure it kept running. It never quit running.
I flew it to a nearby airport where he rented a hangar so I could fly for him and not have to get and out of the dragstrip with it.

Okay I want to know the full story!

 

[Gary Ward]

Okay I want to know the full story!

Full story? I have lots of story's!! lol

 

[the dude]

By turning it over by hand i would think your saving the valve springs relieving the pressure on the ones that are open. Common practice to back the rocker arms off in the racing world when your down for the season if not taking it apart.It also closes the valve.

 

[Pinecone]

OWT. Springs do to fatigue from being compressed, as long as they are not over compressed.

Spring fatigue based on cycles. So turning the engine over does more harm to the springs that leaving them alone.

You hear this a lot in the shooting world about cycling magazines to "save the springs." But many people have left magazines loaded for many years (many times over 20 years) without issues.