CRJ Takeoffs and Landings

[Beechnut]

Okay, thanks for the opinion, here's another perspective. The airline I work for has NO training or procedures for the use of aerodynamic braking. Our procedure strictly state the reverserse are to be used when the aircraft lands down to 80 knots. The reverses are to be reduced and at idle by 60 knots and the use of brakes will be introduced then. This is in writing, this is how they want it done.

You mentioned the demonstration you saw where the TR's were open without a spooled engine. The orginal mentioning of the technique spoke of the engines spooled. There is a difference.

I haven't ever flown a Challenger. Have you done this technique in a CRJ? Sounds like we're talking about two different aircraft.

Nice distinction between the Aviatior and the Drivers. Me being the company man, I'm probably just a driver.

S.

 

[cl-65link]

Allowing an airplane to roll long at the airport I primarily fly out of(MSP) will make you absolutely no friends in the tower and very few waiting in line on the ground. MSP has only two primary parallel runways and are in constant use for both arrivals and departures, unless you are there at 2a.m. And yes I know the runway is yours(all of it, if you need it).

 

[Broke in CVG]

We had an ops note re-iterating the the FSM procedure was to wait until the nose wheel was down before deploying the TRs. This "reminder" was a direct result of an incident. Empty plane (ferry flight) with an aft CG.... touchdown nose high and popped the TRs immediately and had a tail strike. I am not saying that I have never seen it done safely, but there is a reason why the FSM lays it out the way it does and this is one example of what CAN happen.

 

[ReportCanoa]

It is BAD BAD form to use so called "aerodynamic braking" with this aero. It is thought by investigators that this MAY cause unusual stress on the main gear and could lead to complete failure of the main beam. It has happened to one north american operator, and more than once across the pond. Eddy current tests have been run at several airlines and found an unusual state of the alloy. Newer CRJ's are equipped with a more substantial main gear...

 

[GCD]

Some very good replies.

I agree, you won't make friends in MSP by rolling out long, but on the other hand, there is reasonalbe landing distance to preclude the slamma-jamma. BTW- I had a good time in IOE.

As far as aerodynamic braking... well, I said derotation and spoilers was for another day...well, today is another day.

In landing a jet airplane, getting the nose down (derotation), as quickly as can be safely done (without damaging the nose gear), is very important. By getting the nose down, the center of mass (airplane's weight) is shifted from behind the main landing gear to over the mains, thus allowing for more friction to be applied to the tires for tracking and braking. The spoilers also become more effective with the nose on the ground. I know, it looks cool to ride with the nose in the air, but it ain't. When you see the long airplanes (B747, 757, 767, MD80) look like their nose is in the air forever, they are actually trying to derotate as quickly as can be done safely in that airplane. It just takes longer to get the nose down in a B747 than it does in a CRJ. If you ever get the chance to see the Boeing Company Derotation tape, do so. It will open your eyes.

My friend above stated that the CRJ's nose gear is like a shopping cart wheel. He's not far from wrong about that. The derotation in the CRJ, as in every airplane, should be done with finesse. The Boeing tape emphasizes that.

Deploying thrust reverse in the derotaion in a high bypass engine airplane is acceptable, depending on the airplane. The high bypass engine doesn't have "buckets" to strike the ground. I know that the B737-200 and MD80 can get a bottom bucket strike on the ground if the reverse is deployed while the nose is still in the air. Coming out of the B747 into the B737, I told the IOE Check Airman to slap my hands if I reached for the T/R before the nose was on the ground. He did once or twice.

I know about the Comair incident. I don't think it was "caused" by deploying reverse thrust with the nose in the air, but I think I know why the FSM wording was changed. It was to get you guys to get the nose on the ground.

Asymmetric thrust in reverse is a concern. On a dry runway, it is managable, as one post above indicated. However, on a slippery runway, I wouldn't go directly into the stops, as on a dry runway, until symmetric spoolup is assured, but maximizing reverse thrust on a slippery runway is still more effective at high speeds than brakes.

Also, remember, and never forget (as my friend said above), that you own the runway when you are on it. Trying help ATC is good, within reason, but it's not your job to fix their mistakes. There is no good reason to risk damage to your airplane just because tower goofed up and put one too close behind you.

 

[h25b]

Sorry to offend you "stiffler", that certainly wasn't my attention. My apologies...

I guess since I mentioned noticing it in the back, that was offensive... So I guess I should mention I used to see it up front also, when I know what the situation was.

As for trying to impress the hot passenger next to me, she was my wife.... (we stopped trying to impress each other years ago
)

And also, If I had a dime for every time I wasn't popular with ATC.... Well, you know the story... Try and remember the whole point of the forum "Stiff", it's informative discussion... Most people, including myself, don't jump in unless we have first hand operational experience on the topic. I think most people are missing "GCD" 's point. That is, when operational conditions allow, I little extra technique, thought, and awareness can make the passengers experience and the aircraft maintenance a little more enjoyable. The latter by the way contributes to the bottom line which, combined with the earlier pays YOUR salary.

There might be a day in the future, like me, that you end up having to be in the corporate world when frightening the wrong passenger can cost you your job or at the very least a regular passenger's confidence.

That's all, again my apologies...

 

[freightdogfred]

Takeoff thrust setting - There are some very good reasons why your FSM or FCOM says to advance the thrust to 70% N1, stabilize, then set takeoff thrust. The stabilization at 70% N1 is to allow for symmetric spool up. Both engines may spool up to 70% N1 at a different rate, but once stabilized at 70%, it is more likely they will spool to takeoff thrust more evenly. Also, by allowing the engines to stabilize at 70% N1, you are checking two other things, proper airflow through the compressor and that N1 is speed controlled to avoid an overspeed when setting takeoff thrust. Setting takeoff thrust from idle is really poor technique and even causes impulse stress to the turbine blades, causing a creep in the blades and eventually failure of the turbine blades, if done very many times.
.

While setting 70% is good technique to ensure symmetrical and stable engine operation, it will do nothing to eliminate turbine bucket "creep" or "stretch". This is a function of repetitive heating /cooling of the metal, and until you see ceramic turbines, you won't stop it. If you wanted to reduce "creep" and extend turbine life, you would be advised to employ a similar technique at the top of descent, reducing power in increments, vs. going from cruise power to idle. I don't fly the CRJ, but most FMC'S calculate profiles on fuel savings so if your a/c has autothrottles, ther's not a lot you can do.

 

[GCD]

Freightdogfred,

You make a very good point about TOD thrust reduction. However, I was talking about impluse stress creep by going from idle to takeof power. It's from GE, not me. It's something to do with going from 400'C to over 800'C in a couple of seconds. The turbine blades are exposed to rapid heating and rapid centrifugal force simultaneously. While it may not hurt the engine if done a few times, over a period of events, the engine life is reduced.

Also, I know the Comair FSM addresses this, but I know a particular FCOM that does not. That is, after start, the CF34 engine must be at idle thrust for two minutes prior to takeof thrust being applied. That also from GE.

As for those of you who think there is no such thing as premature braking - I didn't make those figures up. The figures came from airplane and brake manufacturer test results. However, you fly your airplane the way you want to. I am only offering my two cents worth of advice. Take it or leave it. I am always open to advice, myself.

Also, I am not saying to not use the brakes, as someone eluded. I advocate, as the brake manufacturers do, to make a firm steady application at 80 knots. A brake, by definition, is a machine or device that converts kinetic energy into heat, then dissapates the heat into the atmosphere. Therefore a single firm application produces less heat than a prolonged application, especially a prolonged, light application, as in taxiing.

Beechnut, your company has it right!

 

[ClearRight]

I'll chime in on the incentive to wait until the nose is on the ground before revving up the reverse thrust. I've got about 700 hours in the RJ and until last week I'd frequently do the "shuttle landing"- mains first, fly the nose while bringing the reverse levers up. Last week I landed fairly light so the nose was rather high, I held it up and added reverse thrust. It wasn't immediate, but I ran out of elevator with the nose wheel still in the air. WHAM. I'll not do that again. From now on, it's nose down, THEN bring in the reverse- just like I was taught!

 

[HighSpeed]

What about heating the brakes??

Good thread on the use of reverse thrust, but I was told that heating the brakes by using them more during landing will extend the life of the brakes. ie.) the carriers in Europe that do not use reverse thrust at all, yet enjoy longer brake life than thier U.S. counterparts because they have to stop using brakes only.... If revrse thrust is used primarily, the brakes will not have "warmed up" and therefore will have excessive wear while "taxiing in" to the gate.....