Question for E-170/190 drivers
 

In cruise flight, is there anything in your SOP's against selecting CON on the TRS to maintain higher airspeed and not get the LIM flag on your FMA?

We're having two different schools of thought:

1) Selecting CON merely allows the engine to use more power only if it needs to, and it doesn't lead into exceedance if it does use the power beyond what's allocated under normal CRZ setting.

or

2) If it was intended to be that way, CON would equal CRZ setting, therefore leaving it in AUTO/CRZ is the only way to do it.


Thoughts?

If CON setting is anything like the 145 (which I'd imagine it would be), then the answer would be no! No you should not use CON unless you're in an emergency situation. CON thrust setting makes the engines work at a much higher temperature than intended, thus causing much more wear and tear.

There have been cases at certain companies (I won't mention which ones), where guys rode CON on climb out all the way, in one case for up to 30 minutes and nearly fried the number 2 as per mx records.

So, in short CON should be for emergency situations only, i.e. single engine.

Max continuous mere means the engine can run and run and run and not burn out. Doesn't say anything about doing it efficiently or allowing it to meet TBO times. I imagine you won't risk poping one ever while flying but you certainly won't make the maintenance guys (or the accounting department) very happy.

I fly the 145 but watch your temps when you select CON. If your temps jump then you're working against yourself unless you need it. Temp=wear on an engine=more cost to your company. Higher output=more fuel burn= more cost to your codeshare. I don't know how much quicker the engine would wear but I'm sure it's significant.

What's wrong with LIM on the FMA? Above about 30k the thrust ratings are almost all the same N1 anyway. It should stay in CLB-1 or 2 until it speeds up to the selected cruise speed, right?

Just like the 145, CON & GA are the same thrust rating. At my last company (the 145), we were prohibited from selecting CON unless directed by the QRH. At Compass, nothing prohibits us from selecting CON on the TRS page, but there is no normal situation that calls for it.

If you're selecting CON for normal Ops, you need a good chat with a CP and MX guy. Are we really that dumb??

I agree, but one difference for those unfamiliar with 170 is that unlike the 145, 170 has autothrottles, so selecting CON merely allows autothrottles to cross the CRZ threshold but not exceed max continuous threshold.

Yeah, you stay in CLB-1 or 2 until you reach your cruise speed, but if your speed drops off later in cruise and you get the LIM on your FMA, my question is if there's anything that states that it is not recommended.

The only time I've used CON power is in the sim when it's called for on a single engine climb out. We use climb 1 on a pretty regular basis and only get LIM if we're climbing in V/S or FPA modes. You won't get LIM in FLCH mode. The 170 climbs a lot better than the 175 when we're heavy, so you will normally see LIM in the 175 when you're trying to maintain 290 in the climb and at least 1500'/minute above 27K or so.

You know whats really sad about this thread..... E170/190 in the REGIONAL forum. No regional shold be flying 170s or 190s, and I can say that because I fly for a one!!!

The best thing any pilot can do in any "normal" situation is to just stick to the book. If something (anything) happens and they see you had the engines configured improperly you'll have quite the carpet dance in front of you. Worst case the plane won't cruise as fast, oh well.

RAH is no longer a regional so that just leaves Compass.:D

Now with the help of Frontier, Midwest, and our own pilots, lets strive for a great contract flying the 170/190.

Oh, if you use CON for cruise flight, you are too high. Do not use it unless single engine

if you are flying in cruise with the LIM on you will also have the eyebrows up...you might be to high for cruise.

If you are increasing speed once you level off the CLIMB 1 will be enough to get the LIM to go away

From an outsider:

1) Does doing this raise your ITTs?
2) How much of a speed difference are we talking about?


If the answer is "yes" and "less than thirty knots," it probably isn't worth it.

1. It depends on what setting you're already in and in what phase of flight. But most likely, YES.

2. Kinda a vauge question. But I think people were using this setting to climb faster at a set speed. Or using it to get to cruise speed faster when leveling off. I wouldn't recommend it.


There is a reason for 2 different settings. CON is for max continuous. CRZ is for cruise. If they were interchangeable, then there wouldn't be 2 settings. Fly by the book. The only time we call for CON is in a single engine operation.

Useless response.

Why would you want to cruise at a speed that requires CON power anyway? What's the rush, unless it is the last leg? Plus, I've never had a problem cruising at Mach .81, so I don't see a reason why CON would ever get used in normal ops.

DING DING DING DING DING........

Somebody gets it.....

My company's SOPs have normal cruise limited to M.78 or less, for improved fuel economy and less wear and tear. Economy cruise is usually slower than that, depending on cruise alt, weight, etc. CON should be used only in emergency situations...that is its sole purpose. It is normal for us to see LIM briefly upon level off at cruise, but just for a few moments as the speed catches up. Hope this helps:)

To add to this...LIM appears when the actual speed is 5 kts or more less than the set speed in a climb (or greater than 5 kts in a descent). As you said, LIM only functions in FPA or VS, and so if it appears, the selected FPA pitch angle or VS climb rate is more than the engines can provide. The first thing that comes to mind for me is Pinnacle...why ask for a climb rate or pitch angle that results in a deteriorating airspeed? If level and the aircraft won't accelerate to or hold the selected speed, then the pilot needs to rethink the situation.

CON is an emergency power setting only according to Embraer. If someone is selecting CON to solve a cruise or climb speed issue, I suggest they refer to the performance manual for gross weight limitations.

From Embraer

I don't think "LIM" on the FMA qualifies as and "emergency situation".

Normal Go around trust is limited to 965 ITT for two minutes and 949 ITT for an additional three minutes. CON thrust is limited to 960 ITT continuously. CON is essentially take-off thrust indefinitely. I'm guessing this is not a good thing.

It's basically the same. The 145's FADEC will not allow you to exceed CON either if selected.

What R U smoking ?

Wow when did that happen??? Did you guys get a new contract with mainline wages/benefits/retirement that we didn't hear about (and no you can't count Midwest & Frontier's as yours)??? Pass the pipe if not!

i have a feeling this thread started out with good intentions

I was kidding:cool:

Which part??? :confused:

Other than the two or three flame baits, this is the most professional thread that has been on here in months. If we would all worry a lot more about professionalism and improving pilots' working knowledge, perhaps we would not have to worry about pilot pay and quality of life as much.

Thanks for a refreshing break from the bottom feeders.

Right, but at higher altitudes, if you're in CON and you're above the threshold of CRZ settings, your ITT is gonna be around 770-790 or so, and in CRZ, it'll be around 750-760 - nowhere near the limitations.