Zootrix From United States of America, joined Nov 2005, 86 posts, RR: 0 Posted (8 years 1 month 1 week 18 hours ago) and read 4460 times:
While flying on a Comair CRJ100 between BOS-BGR, we were cruising (FL150-180) on one engine. Sitting in 12 D, you can rotate your neck by 180deg. (almost) and see the right engine (# 2??). The fan was not rotating. I checked repeatedly and NO, the fan was not rotating!! I even tried taking a pic. but could not due to scratches/haze on the plastic and glass of the window. Now taxiing on one engine is common practice, but how common is this method of conserving fuel, esp. in light of Delta's bankruptcy and Comair's financial woes?
Back in the 80s, I had heard the FAA penalizing some US airlines who were trying to save fuel by switching off 1 or 2 engines while cruising.
Tornado82 From , joined Dec 1969, posts, RR: Reply 2, posted (8 years 1 month 1 week 18 hours ago) and read 4375 times:
The CRJ is lucky to have enough power/lift to fly with 2 engines... they wouldn't be shutting one down for sh*ts and giggles...
That said, some engines, when running at a certain speed, the fan gives an appearance as if its not moving. It's an optical illusion caused by the refresh rate of your eye, similar things happen when you look at wheels on a car going by sometimes. I once noticed this on a NW DC-9 before too. Made for a nervous second or two.
Zootrix From United States of America, joined Nov 2005, 86 posts, RR: 0 Reply 3, posted (8 years 1 month 1 week 18 hours ago) and read 4334 times:
Agree with Tornado82 about thoughts on optical illusion, but I did check the engine repeatedly just to make sure it was ruled out. I have seen CRJ and EMB turbofans in action while in flight, so I'm absolutely sure the engine was OFF in this case.....dead sure!
EMBQA From United States of America, joined Oct 2003, 9354 posts, RR: 12 Reply 4, posted (8 years 1 month 1 week 18 hours ago) and read 4324 times:
Sorry dude, no way..... If they had shut down an engine in flight you would have known it. Your flight would have been greated in BGR by a parade of fire trucks, you would have lost pack air cooling and the flight crew would have announced it. What you might have been seeing is the Stators in the engine. They do not turn and in some lighting conditions and angles you can't see the fan blades spinning, only the stators.
"It's not the size of the dog in the fight, but the size of the fight in the dog"
Tornado82 From , joined Dec 1969, posts, RR: Reply 6, posted (8 years 1 month 1 week 18 hours ago) and read 4300 times:
Quoting EMBQA (Reply 4): What you might have been seeing is the Stators in the engine. They do not turn and in some lighting conditions and angles you can't see the fan blades spinning, only the stators.
I thought of those too, but they didn't seem as noticable in any CRJ I've ever been on as opposed to some engines... not to mention I didn't know the technical name of them and didn't want to look like a dumbass
AA737-823 From United States of America, joined Mar 2000, 5547 posts, RR: 11 Reply 7, posted (8 years 1 month 1 week 18 hours ago) and read 4271 times:
This is NOT the same thing as what you can see on a DC-9, but way similar.
The DC-9 has IGV's- inlet guide vanes- in front of the fan. They don't turn, and give the appearance of the engine not spinning.
In the case of the CRJ, you were seeing the stationary stator vanes BEHIND the fan. The fan was spinning to the point that it looked like it wasn't even there- and you saw the stators behind it.
It's not legal to operate a part 121 transport cat aircraft with only one engine. Not to mention stupid.
Now thats one thing thats a totally new concept to me. Am I missing something.
Btw: A buddy told me that they were operating on 1 engine (fan not turning, plane rolled a little towards good one etc.) for a short flight. There are some regs. (part 121) that allow airlines to operate (or continue would be more appropriate) a flight for certain distance (which is pretty short) on one engine.
Swmdal From United States of America, joined Nov 2005, 36 posts, RR: 0 Reply 10, posted (8 years 1 month 1 week 14 hours ago) and read 4072 times:
A Comair captain told me she once had to shut down an RJ engine in flight because of overheating. They were fairly close to their destination at CVG, so they just continued on without making any announcements and landed normally. Was it legal? I don't know. I guess she didn't want to cause a panic by making an announcement.
UAXDXer From United States of America, joined Jul 2004, 765 posts, RR: 3 Reply 12, posted (8 years 1 month 1 week 7 hours ago) and read 3928 times:
Quoting Soaringadi (Reply 8): There are some regs. (part 121) that allow airlines to operate (or continue would be more appropriate) a flight for certain distance (which is pretty short) on one engine.
This is absolutly 100% false! Their is no FAR Part 121 regulation that allows single engine operations on a twin engine aircraft. The regs say that you lose an engine due to mechanical failure, the crew is to land at the nearest suitable airport.
It takes a bug to hit a windsheild but it takes guts to stick
DAL767400ER From Germany, joined Feb 2005, 5721 posts, RR: 48 Reply 13, posted (8 years 1 month 1 week 7 hours ago) and read 3917 times:
Quoting Soaringadi (Reply 8): Now thats one thing thats a totally new concept to me. Am I missing something.
DL started doing that fleet-wide after trials at DLX had been successful, and Southwest has probably been doing that for decades now. Usually, the engine is being turned off, as it not only means less fuel burn, but also that baggage handlers and other ground crew can get to the plane way faster than if they had to wait for the engine to spool down, so it effectively also means a reduction in turnaround time.
RJ From United States of America, joined Mar 2001, 198 posts, RR: 1 Reply 14, posted (8 years 1 month 6 days 23 hours ago) and read 3712 times:
As a Comair pilot, I can assure you that intentionally shutting down an engine in flight to save fuel is NOT ALLOWED. Period. If there was a problem and the crew had to do an in-flight shutdown at the altitude that you stated, you would have known about it. The Flight Attendant would have been briefed and you would have as well.
The Part 121 FAR's say that if you have an engine failure enroute, that you must land at the nearest suitable airport in point of time.
Now, with that out of the way, Comair does taxi on the number 2 engine as standard operating procedure. It saves a lot of money on taxi outs. There are times when it is not warranted to taxi on one engine, such as when there is heavy snow on the taxiway or when it is icy. Tight parking spaces (JFK) also warrant taxiing on two engines.
Oh, and the CRJ does just fine on single engine go-around. We practice them in the sim on every checkride. Actually, the CRJ performs reasonably well at low altitudes. It is when it is above 20K that performance degrades.
Nugpot From South Africa, joined Jun 2005, 32 posts, RR: 2 Reply 18, posted (8 years 1 month 3 days ago) and read 3104 times:
One thing you guys seem to lose sight of. If the engine was shut down, it would be windmilling. In other words, the fan would be turned by the airflow through it. There is no way to stop the fan from turning unless the N1 core had seized.
You can even see fans turning in a 5 kt wind from the front on the ground, although they then turn very slowly. At cruise speed you have 250+ kts turning that fan.
EclipseFlight7 From Somalia, joined Apr 2004, 517 posts, RR: 2 Reply 20, posted (8 years 1 month 3 days ago) and read 3079 times:
Like Nugpot says, there's no way to feather a jet engine, so the blade would definatly be moving. The next time your out for a drive, take a look at a car next to you at a stop light and watch its wheels as it accelerates, and you'll see this exact same phenomenon.
Delta Express, to cut down on fuel costs, would have one of the engines (left?) shut off for taxi out and start it shortly before takeoff. On landing they would shut the other one (right?) off for the taxi in, to maintain the general number of hours on the engines.
While having to use a crapload more rudder on the ground, there's no real problem with taxiing with one engine, but there is no way in hell a plane is certified for single engine operation flight when it's multienginei, thanks to the Part 121 regulations. However, I have heard of four engine aircraft flying with three (without passengers, of course) for short ferry flights to go and replace an engine. However, as we've seen with the South African 742 at Rand, a jetliner has a lot of performance to throw around when there's nothing on board.
EMBQA From United States of America, joined Oct 2003, 9354 posts, RR: 12 Reply 21, posted (8 years 1 month 2 days 23 hours ago) and read 3023 times:
Quoting Tornado82 (Reply 17): MHT? or then even PSM or something despite not being a DL airport? I would think if the CRJ had actually lost an engine they would have turned inland ASAP anyways, right?
MHT is just slightly south and west of BOS (departure wise, not physically) and is really no factor. You cross PSM just minutes after departure, so unless your problem happened seconds after departure, it would be behind you as well. The route up from BOS to BGR really doesn't take you over water and for the most part you hug the coast until crossing over NAS (NHZ / KNHZ), USA - Maine">NHZ.. Brunswick NAS then turn inland up to BGR. I've jump seated on that route more times then I can count. It was always a fun ride with a great view...!!!
"It's not the size of the dog in the fight, but the size of the fight in the dog"
Nugpot From South Africa, joined Jun 2005, 32 posts, RR: 2 Reply 22, posted (8 years 1 month 2 days 13 hours ago) and read 2861 times:
Quoting EclipseFlight7 (Reply 20): While having to use a crapload more rudder on the ground, there's no real problem with taxiing with one engine
This is not really relevant on the CRJ. The engines are close to centreline and you use hydraulic nosewheel steering on ground in any case. You would not feel an engine out on ground for taxi purposes.
Just the question of fuel saving. At cruise the CRJ burns 550 - 650 kg per hour per engine, depending on speed and flight level. On one engine, it has to run at max continuous thrust to give you a semi-decent speed. That would mean higher fuel burn plus reduced engine life on that engine (It will have to run at very high ITT, which seriously reduces engine life.)
I can't see any saving being made by shutting down one engine. You might save 50 kg on a shortish sector, but you will end up paying double that in reduced engine life.
I did my annual IF renewal on CRJ 200 yesterday. We spent most of the flight in simulated single engine ops (other engine at idle thrust). You have to burn the live engine to do anything more than 200 KTS and we were operating over Table Bay in Cape Town at 9000' above SL. Plus we were VERY light. 5 crew members on board, no pax, no baggage, no catering.
The CRJ has decent single engine performance for emergency purposes, but the live engine takes a hammering. Bombardier said that every 5 min at ITT over 800 degrees C , reduces engine life by up to one hour.
Sorry Zootrix, I don't want to rain on your parade, but the CRJ100 with the 3A engine will run at even higher ITT's than the -200 with the 3B engine. I just cannot see it making economic, operational or safety sense to intentionally shut down a serviceable engine on a revenue flight.
I wasn't there though. Could happen. I know that airline beancounters are the most dangerous species on this planet.