Fixed wing powercheck!.!.! you what?

[tegwin]

Im just curious really...im PPL (H), but have a really daft question for you fixed wing people....

What exactly is a 'powercheck' in a piston engined fixed wing aircraft? And how does one "fail" a power check?



In a piston helicopter, the Mags are checked to see if they effect the Rotor RPM, but this takes only a few seconds to determine the efficiency of each Mag...

[BackPacker]

Well, in a piston A, it's the same thing. Depending on the exact type, power checks may or will include the following:
- Magnetos check
- Carb heat check
- Full power check
- Prop cycle check
- FADEC/ECU check
- Idle check

[waldopepper42]

In ours, at 1100rpm you check engine temps and pressures are in the correct range.

Then you check that the engine keeps running on each mag in turn.

Then increase rpm to 1800, check temps and pressures again.

Check each mag in turn, that the drop in rpm does not exceed 150rpm, and that the difference between the two drops is less than 50rpm.

Have a last glance at ts and ps and reduce to idle. Check correct idle rpm (750ish), and back to 1100rpm.

There's some other stuff to do with cycling the prop., but that's not really part of the power check.

OOps, backpacker beat me to it!

[gcolyer]

Cycling the prob is for wobbly prop's and is definatley part of the power checks.

[waldopepper42]

Ok - slightly pedantic, but it checks the operation of the prop governor, not the correct operation / power of the engine.

It's done at the same time as the power checks though.

[dublinpilot]

Check suction guage, amp meter, and fuel pressure/pump too.

[effortless]

You make sure that you blow grass and dust into the bar.

[Gertrude the Wombat]

And how does one "fail" a power check?

In my case the engine only just keep running on one of the mags, a clear fail.

[BHenderson]

Heli Run-up

Helicopter (R22) Checklist

Engine t's + p's
Mag Drop
Alternator
Carb Heat
Sprag Clutch
Low RPM Warning Horn

Governor (CSU) is working if it maintains top of green band
Engine running at flight idle is same as idle in aeroplane
Engine runs at full power in the hover so you check t's + p's when you first lift into hover
No fuel pump (gravity drain)
Electric Servos so no suction

No timmer to check
No throttle friction
Primer rare on R22s
No control freedom check when running!
Mixture Guard prevents leaning
No Pitot heat, unless in an IFR trainer
No Flaps

[tegwin]

Only reason I asked is that I hear on the radio all the fixed wing people talking about power checks and felt a bit left out

But I need not worry, its looks like its all the same...ish...

[Schmacko]

Tis'nt true lads
The short answer is that power checks relate to the RPM achieved by the engine at a given MP, now given that as QFE varies so will available MP, therefore the best solution and the one used by round engine operators is;
........when engine warm
........complete all cycling and other checks
........increase MP to field pressure
........engine RPM should be within specific range ie max....min
........therefore a certain amount of power is being developed, ie static thrust
For example my engine is field pressure at 2150...2250 RPM therefore it is delivering a certain amount of power see your POH

Smacko......good for dogs

[BackPacker]

Schmacko, that's only true if you have a fixed pitch prop set to the correct pitch. With a constant speed prop you can reach max RPMs (full fine) with only, what, 10% power?

Anyway, let's not call 'em power checks but run-up checks, follow POH guidelines and be done with it.

Tegwin, for fixed wing light aircraft it is common to do the run-up checks at the hold, so that other aircraft are not blown away by the prop wash. Plus, on long taxis you might foul the plugs if you don't lean properly while taxiing. But doing these checks at the hold means that you might be holding up the aircraft behind you, so you might hear the occasional communication about this. ("G-XXXX, ready for departure? Negative, not finished the power checks yet, G-XXXX.") For helicopters the situation might be different since you do them before and when you lift into the hover.

At the end of the day, the checks are more or less the same for piston fixed wing and fixed rotary: mags, carb heat, t&p, idle. In the fixed-wing world we also do a full & free check of the controls, which gets kinda interesting and expensive in a helicopter once the blades are spinning. And there's a little variation because fixed wing either means fixed pitch (throttle impacts rpm directly) or constant speed (throttle increases power, which increases rpm, which prompts the prop to get more course, reducing rpm), but in a heli you're using a governor (collective increases pitch, which increases drag, which decreases rpm, which prompts the throttle to open, increasing rpms again). That might make a little difference in the procedure for the mag check.

[glazer]

Power checks

In an aircraft like a Cirrus with a fuel injected engine, there is much more that one can get from a high power check. To do this you need a gauge that reports EGT values for each cylinder. The test is preferably done with the engine mixture leaned (this accentuates any faults). On switching to a single mag at say 1700 rpm all EGTs should rise and eventually become steady. If one of the EGT's drops this usually signifies a plug fault. If all EGT's drop then it is likely to be a mag fault.

It is even better to conduct this test during flight!

[Schmacko]

NoNoNo boys
Power checks are predominantly the domain of high power radials and vee's
for example I do power checks on 1450 hp radials it is a pre flight requirement, I do believe we are probably talking different things here, I've run out of time.........but let me assure you power checks are relevant to all engines......If I want to know the general output of my TSIO520's I will do a power check..........read old Curtis Wright, Lycoming, Merlin and Packard manuals they will tell you all about it.

Gotta go
Smacko....goodoh for dogs

[cotterpot]

You are also checking that the fuel tank you have just changed over to (in a PA28) will deliver clean fuel at the required rate to enable take off.

[Shaggy Sheep Driver]

Some aeroplane drivers do make a bit of a meal of power checks. It can be done perfectly well in a few seconds, but these bozos sit blocking a taxyway or a fueling space in their very simple spam can while they run v-e-r-y s-l-o-w-l-y through a checklist that would do justice to a space shuttle.

[bar shaker]

SSD

I normally find that wait until I have taxied up behind them before they check that they are getting full rpm.

They then turn 90deg to the taxywayand finish the checks.