It is the same with most Jets, 3mins cooldown at idle to stabilise - usually covered by taxi in, if not then slowdown taxi or short time stopped.:ok:
[clock started after coming out of full reverse - idle reverse shortens the time by adding all the roll-out time!]:rolleyes:

Tank Engine, Quite right the taxi time will always do it, temps stable.

OK.......time for some thread drift :ugh:....... let a few of you cool your Turbo's down for a 2-3 minutes!

Who says you can't run a Carby Fixed Pitch plane LOP?

http://i849.photobucket.com/albums/a...0/IMG_0630.jpg

Now this is one of several trials of different settings, and this was taken just after TOC, the CHT's started rolling back, and yes CHT3&4 are a bit high, some tweaking to baffles and things need to be done, and the TAS had not settled from a few bumps, but check out the details.

The TAS stabilised at around 150, the fuel flow was around 29 LPH, the cylinder spread was was pretty good.

PLEASE IGNORE the fact the EMS thought we were operating ROP, I had been playing around with different settings and it thought we were ROP, I had to drive it well rich again and lean back again to get that to change. 29lph is definately LOP.

No Turbo's today, that was yesterday and it seemed to attract hail storms :hmm:

Turbo Cool Down
 

Interestingly, the Cessna 404 manual says,

As said the taxi in would cover it, thought the ground run part of interest though. If I recall correctly the turbo Bell 47 helo required 5 minutes after landing.

Jaba Who says you can't run a Carby Fixed Pitch plane LOP?

Nobody who knows what they are doing, and I note you have run out of MAP at 8500 ft interesting cylinder numbering , 2 number 3.

The owner/operator of the C402 that I used to fly told me during endorsement training, "Run them at idle or just what you need to taxi for 3 minutes after touchdown - so I did!

He let me fly his very nice executive config C402 - and I did as I was told. Simple!

Dr :8

Thanx for that T28. Nice to know that what I am saying makes plausible sense to someone. However I am not going to go so far as to suggest that he is an FS pilot. Probably one that flew turbo pistons a long time ago on OWT's, and has since forgotten to look at whats being offered objectionally.
I've made a couple of posts on turbo cooling through this thread, and I only hope he goes back and reads them with an open mind.

3 weeks ago I might have agreed on the cool down time. Since being pointed in different directions by a plethora of people here (no names because i will forget one) I have learnt a lot.

Even when i have disagreed, I have at least gone and looked at the data and used my head to think about it!!


Fanboy.............777 jockey........... you presented an article that is 14 years old. go ask the author to re-write it with stats and figures that they know today......you might be surprised.

Jas

Flight instructors :D


TBH, i normally run ROP (best power) as the money making muppets who control the prices I pay (do NOT get me started on that hobby horse) want me to pay VDO wet. So i am gunna squeeze every extra knot i can out of it, and f*ck your fuel bill..........i am now only interested in my bill.


Give it to me on airswitch, i'll run it LOP and even peruse the AFM inflight to squeeze every MPG out of it i can.

Jaba and Clinton,

Just asking a question.

Yet to work for a single PA-31 or C400 series operator (there's that commercial vs private operator thing again) who would accept an immediate shutdown (taxi time notwithstanding) without telling the pilot to find a new job.

Any commercial operators out there seen otherwise?:confused:

Jas:
The only stipulation I would suggest for LOP operations would be make sure you are using a multiple-point egt/cht system. :ok:

Further to MIHC's post, is LOP/Oversquare operations used often in the charter mobs around the place? Or is this the domain of those unprofessional PPLs who don't bother knowing the important details about their plane? :E

Don't get me wrong McGrath, LOP is a perfectly valid mode of operation and is actually factory spec procedure on several a/c such as the Piper Malibu (50F LOP). From memory, Deakin strongly promotes this kind of operation for Contis in conjunction with Gami injectors; much kinder to CHTs on the lean side of the egt peak.

Likewise with over square. If a manual specifies power settings, they aren't going to hurt the engine. If an operator specifies a power setting to be used in an ops manual, it is unlikely to be detrimental to the engine. If it happens not to be the most efficient way of running the engine, you aren't paying the fuel bill.:ok:

I spoke to a Queenstown NZ pilot a while ago who flew 206s and 207s. When he said they flew them LOP my eyes almost feel out.

All this thread drift whilst educational is really dodging the real bogey which in my view is a lack of understanding of the management of piston engines around detonation.

Lots of talk re leaning and oversquare without really bringing the relationship between the amount of fuel in the cylinder/ the pressure it is fed in at/ the RPM of the engine ( load ) /the tempreture of the top of the cylinder.

In talking to younger newbies I sense that the OWT re: detonation are well and truly entrenched in the Grade 3 instructor ranks and being passed on to all newbies as if a cobra were in their flight bag.

No real attempt to understand how the engine delivers efficient power, more a real "keep away from this" as a reference to the engine allegedly melting down before their eyes.

'MakeItHappen' - Skytrans in Cairns was for several years the largest 404 operator in Oz, with 10 404s, 6 310s, 3 Bongos, a SKA and a Dash 8.

Almost without exception, their GTSIO 520s lasted through to TBO. The exceptions were a couple of cylinder failures said to be due to a batch of dodgy base bolts.

In those pre-JPI / EDM days, power was set well RoP via fuel flows with quite accurate FF gauges - full for max power or takeoff, 160pph/side for climb, 110pph/side for cruise. The handling notes and Ops Man state that once power is reduced in the descent, during the approach power can be adjusted freely between 17" to 25" without having any impact on engine temps.

The notes also add that once at these low power settings, this time is included in the 'cool-down' period required in the AFM. For practical purposes given that any approach was at least 10 minutes of low power flying, this meant that unless there was a go-around, a missed approach or OEI ops, then the approach, landing and taxi (which was at 800RPM unless the electric aircon was on, which required 1000RPM) constituted more than sufficient cooling time and once the aircraft finished taxying it was shut down immediately.

Having watched a new TIO540 undergoing test runs on a rig with the exhaust end of the turbo open, I can also state that low power ops do not come close to spinning up the turbine.

As has been said already, if you are paying for the maintenance, you might want to consider these concepts. If you're working for an operator, do it their way. Maybe you could have a conversation with them about it.

For the record, it wasn't me who deleted my last post. The Mods, I guess. :ouch:
(Perhaps I shouldn't have addressed T28D by his christian name)
and Clinton if you're talking to me, ????
This message is hidden because Clinton McKenzie is on your ignore list.

Lovely concept Jas, I'm hoping you never have the pleasure of using one of my aircraft .... may your wings fall off in the turbulence one day while you are charging across the sky in your ignorant bliss. :ugh:

LOL avgas,

Squeezing every knot= ROP correct :)

Sure, i will slow down to turb penetration speed if it calls for it, coz i don't fancy flight without wings.....

But owners/operators who want to charge MAX dollars, bumping up the price simply because (reason removed), then want you to pay through your arse for an aeroplane that the comm's are dodgy, the half the knobs are missing off the transponder, the GPS database is 5 years out of date, the ADF still points 90 degrees away from the NDB (6 months after you wrote it up), half the trims are coming off, the thing stinks like a mouldy apple because it leaks like a bottomless bucket..........................need I go on?

Its apples for apples isn't it.
Show the client you respect your machine by investing some of that price gouging, and your client will show due dilligence in operating it.

Cheers
Jas

Hi Jas, Yeh I was probably a tad harsh in my approach, however (as a previous thread on costs shows) it's not all beer & skittles for the aircraft operator either,
so may your wings be structurally sound & your beer cold at the end of the day.
cheers :E
A172

No probs,
i'm just a dumb :mad: panel beater, so i can be a bit dumb in how i present things :p

It just drives me mad when the owner of a POS thinks he can charge the same as joe up the road, who has impeccable aeroplanes. They really do wonder why people don't want to use them, and treat them like junk when they do.

I still recall the owners surprise after returning his aeroplane after a 2 week trip to the centre, I came back the next day and fully cleaned it. Back to the way it was the day I collected it....

anyway....BOT

Awww come on mods. Please put the 2nd last line of my deleted post back. Jas just confirmed it with his last few posts. Hahahaha.