Engine start best practice and POH caution

[hazek]

Could someone shed some light on this caution from the POH:

I would like to understand how important this actually is and how strict is the limit of 1000RPM. I'm asking because my maintenance shop, when for example doing an oil change, will in 5°C OAT do this:

 

^ This was a runup by them.

Am I being too anal for being bothered by this? I specifically told them to perform the runup according to the POH after they did it like this the last time:

Note the high RPM immediately after start, the full! power runup, the two normal runups and then nearly immediate shutdown. ^ This was performed post last annual during summer so ok, not as cold outside.


This all fine? Am I being worried about nothing? Am I complicating things for trying to get them to adhere to the caution in the POH?
Thanks!

[Fritz1]

everybody has their own way of doing things, 2000 rpm on cold engine not good though, I preheat below 50F if I can, which should add to about 10C, mixture rich, full throttle boost pump injection for 4-6 sec depending on temp, gotta feel it, throttle close, open throttle 1.5-2 turns, start, she usually fires within one revolution and runs at about 1000 RPM, immediately lean as much as you can to keep the plugs from fowling, keep RPM at 1000, I have a slick start mag booster, $1000, run 3 wires, solves in particular hot start problems, taxi out at 1000-1200 rpm, for takeoff you want at least 160 dF oil temp for the density controller to work right, otherwise good chance for overboost at full throttle and bootstrapping when reducing power especially with single weight oil, the Slick mag booster, tempest fine wire plugs and Phillips XC work well in the Bravo engine

[Jetpilot86]

Obviously an oil temp overlay would come in handy here, but I've noticed in my Bravo it doesn't take long to get to that min oil temp either.  1200 RPM doesn't give me heart failure as it takes me a second or two to get that right when I start.  If that was the runup AFTER the fresh oil was put in, likely the Oil was close to the 75dF you desire since it probably came from inside vs sitting in the sump, outside, overnight.

I run Phillips X/C 20/50, Fine wires, but I have dual SureFly mags, which are a game changer vs the Slicks un-reliability.

[Slick Nick]

Running a cold engine to 2000 RPM less than 4 minutes after start is unacceptable. What the hell is your shop doing? Your graphs are very telling. 

[varlajo]

My ignition key seems to mysteriously fall off the keychain and stay in my pocket when I drop the plane off for service.. oops.. 

[Fly Boomer]

17 hours ago, hazek said:

I specifically told them to perform the runup according to the POH

Many Mooney drivers specifically tell the FBO to tow their Mooney according to the POH too, but the ramp rats continue to destroy our nose gear trusses.

[hazek]

I appreciate the engagement so far but really, I would just like someone knowledgeable about engines to shed some light on that caution and how to understand it. Anyone?

[Fritz1]

there is no straightforward answer, it depends, 1200 rpm upon startup at 70F - 20C won't hurt anything, engine runs smoother than at 1000 rpm, components warm up at different rates, hard to tell when 2000 rpm is really permissible, think the POH says oil should be 100F for takeoff, don't remember the CHT number right now, but there is one, when these numbers are reached 2000 rpm certainly won't hurt anything

[Slick Nick]

2 hours ago, hazek said:

I appreciate the engagement so far but really, I would just like someone knowledgeable about engines to shed some light on that caution and how to understand it. Anyone?

The reason behind the caution is that things heat up at different rates. The block is a huge chunk of cast iron, the pistons are aluminum, most moving parts are steel, cylinders and liners can be different. They are all designed to work best at operation temperature. That’s why the oil and CHT gauges have a green range. As much as there is a maximum, there’s also a minimum. Pushing things too hard can cause clearances to tighten up dangerously and cause damage. I’ve seen a few engines that were pushed too hard when cold, the aluminum pistons expand much faster than the rest of the engine. They can only expand so far before the contact the cylinder walls, and then you’ve got some extensive damage. (Google “collapsed piston” for more.) 

In addition, when oil is cold, it doesn’t flow as well. It can lead to bearings, journals, etc losing adequate lubrication and before you know it you’ve scuffed a bearing or galled a cam. It happens. 

Now, I’m not saying it happened in your case, there’s only one way to know for sure and that’s to inspect things. But engines are expensive, you better believe I’d be some kinda pissed if a mechanic ran my engine the way he did yours. I take extreme care to “baby” my engine until it’s up to temp, to have someone undo all of that work in a matter of minutes would have me pretty miffed. 

[Slick Nick]

I just saw you’ve got a Bravo. They sure didn’t do your turbo any favours either with that stunt. 

[Fritz1]

Well, the bottom line is: if you can avoid it at all cost, don't let anybody tow your airplane or run your engine unless you are there, factory reman Bravo engine is the better part of $120k and at least one year backorder, let them call you anal retentive

[hazek]

14 hours ago, Slick Nick said:

I take extreme care to “baby” my engine until it’s up to temp

Same. And the frustrating part is that following the POH checklist for starting it you can start it at sub 1000RPM very easily every single time!

[Slick Nick]

2 hours ago, hazek said:

Same. And the frustrating part is that following the POH checklist for starting it you can start it at sub 1000RPM very easily every single time!

So, what's the resolution you're looking for here? Are you attempting to seek damages from the shop? I think what's done is done, it would be super hard to prove any damage caused was due to their reckless runup anyway. What's the end goal? 

If it were me, I wouldn't be going back there if that's how they treat customers airplanes. 

[LANCECASPER]

15 hours ago, hazek said:

Same. And the frustrating part is that following the POH checklist for starting it you can start it at sub 1000RPM very easily every single time!

The problem at shops is that they work on a lot of airplanes, each of which has its own quirks in starting. Partially through the POH, but mainly through trial and error, we have all figured out what works with our individual airplane - and many times that varies with airplanes that are the same model and sometimes requires prayers and sacrifices to the aviation gods when hot starting some models. The likelihood that a shop will get it right starting it once or twice a year is not good.

You’re not really going to change the way they do things. If the way they do it bothers you, and your schedule allows, just tell them that you want to be there for start-ups. You’ll both be happier that way. 

[hazek]

2 hours ago, Slick Nick said:

So, what's the resolution you're looking for here?

I stated my question clearly I thought. 

 

On 2/22/2026 at 10:03 PM, hazek said:

This all fine? Am I being worried about nothing? Am I complicating things for trying to get them to adhere to the caution in the POH?
Thanks!

 

[affricate]

On 2/23/2026 at 8:30 AM, Fly Boomer said:

Many Mooney drivers specifically tell the FBO to tow their Mooney according to the POH too, but the ramp rats continue to destroy our nose gear trusses.

Very true, 

[Bolter]

On 2/23/2026 at 1:51 PM, Slick Nick said:

The reason behind the caution is that things heat up at different rates. The block is a huge chunk of cast iron, the pistons are aluminum, most moving parts are steel, cylinders and liners can be different. They are all designed to work best at operation temperature. That’s why the oil and CHT gauges have a green range. As much as there is a maximum, there’s also a minimum. Pushing things too hard can cause clearances to tighten up dangerously and cause damage. I’ve seen a few engines that were pushed too hard when cold, the aluminum pistons expand much faster than the rest of the engine. They can only expand so far before the contact the cylinder walls, and then you’ve got some extensive damage. (Google “collapsed piston” for more.) 

In addition, when oil is cold, it doesn’t flow as well. It can lead to bearings, journals, etc losing adequate lubrication and before you know it you’ve scuffed a bearing or galled a cam. It happens. 

I expect these are the 2 mechanisms of concern.  That said, I would think CHT would be a more useful indication of the engine metal heating.  Since it is oil temp, I have a bias this is about oil circulation.  Even more so with a turbo engine.  Using multi-weight oil would solve this issue on cold days.  The POH as a "catch-all" may assume single weight oil, which is permitted, instead of giving a range of limitations based on a range of possible conditions.  

[dzeleski]

Was the airplane inside and then towed outside to do the runup? Its possible the engine and oil was already at 65-70F depending on the inside temp of the shop. What were the CHTs or Oil temp at the start of the datalog?

If your engine monitor like mine is on your avionics bus you can start the engine without turning on the engine monitor. So it could look like it was started because you flip both switches but its possible they did not flip the avionics bus online until several minutes later.

[skykrawler]

If the shop is only doing an oil change there is no need for a runup.   Running the engine is just to check for leaks.

After servicing plugs, typically a runup is done.

During an annual a full static power check (for RPM) is sometimes done on fixed pitch aircraft.  Constant speed full power runup I would think would only be done statically if there was a problem being diagnosed (or Continental engine fuel setup) - especially for high horsepower engines.

Full power runups are a good way to ablate the propeller and get rock nicks.

My handbook says don't runup 'until the oil temp is 75 or above the white dot.'  Turbo charged engines should probably be a bit higher for reasons mentioned previously.

[hazek]

I use Aeroshell w15w50. The oil might have been warmer than OAT, true.

On this latest runup, after the latest oil change, the CHTs started recording at between 71 coldest and 100°F hottest. On the runup from the last annual during summer, the CHTs started recording between 154 coldest and 171°F hottest. So yeah this time they were way colder at start. Unfortunately the OAT reading, or at least I think this, is a squawk. I have to have it looked into, so I don't know if it's working correctly right now, so I can't know what the temp exactly was at that day but I have a reading of 3°C for this last runup. And that tracks with the temps we had around that time. So it was cold.
Btw during the summer runup the CHTs peaked like this:

Mind you I never allow my CHTs to come above 380 during normal operation, ever, for an extended period of time. If I reach it, I do something to get it back down below 380°F.

So I'm gathering the consensus is that I'm not being anal but also that this is just the way it is?