I fly the RJ, Discrepancy list
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@rj during the engine start sequence what's a realistic spool time to idle and starter cutout?, having dispatched thousands of real world RJ's i feel like the engine start time on the JF aircraft is a bit sluggish. Also given the engines are started electrically is it really crucial that the APU air is turned off?, i noticed that when i would fly off the mine site on a 40+ degree day the crew would be blowing the air conditioning as to not cook us in an already warm cabin filled with a million flies.
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@GeographicalInvert
You are absolutely right! I had noticed it felt sluggish too. Especially the initial 0-10% N2. We start a timer once the starter is operating and you can expect around 25 seconds for starter cut out. Older starters take longer and if the oil is cold it also takes a bit longer. Cold Start isolates the DC bus bars and boosts the Transformer Rectifiers from 28 to 36 volts, this significantly increases starter torque and reduces start time. Max motoring speed with normal start is about 18% N2, max motoring with cold start is about 22%.On the topic of starting, that chirp sound you hear on engine start should happen 1 second after pressing start and the starter operating light coming on, the first second is a “soft start” to remove slack from the gears, and after that second the motor applies full torque which causes a noticeable temporary dip in voltage and frequency from the power source. Neither the soft start delay nor the voltage and frequency dip are modelled. Also during Cold Start there should be no chirp sound, but I think Cold Start just isn’t modelled at all at the moment.
I’ll record real times tomorrow and should have them up by midnight (UTC-4)
APU AIR only needs to be off if you start with the APU. Otherwise you can keep it on but you will get a jet fuel smell in the cabin. After engine start you don’t smell anything because you get a clean fuel burn.
It’s also our SOP- which is based on Swiss OMs- to turn off galley and brake fans to lower electrical load.(Even though galley is automatically shed during start)
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Hello and great to have you here,
I‘ve got a question too: do you also feel that the ground effect is too pronounced upon flare/touchdown?
To me, with the aircraft being perfectly trimmed on speed it feels like it is flaring on it’s own. No input needed from my side.Is this true IRL too?
Thank’s and best regards!
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@Diamondstar
My setup is too basic to really appreciate the handling. The avro in particular the 85 has a bit of a nose down attitude during approach. Some of my colleagues that have experience in another jets say it really feels like they’re going to wheelbarrow the airplane. The 100 sinks a bit more and has a more nose up attitude.If you cross the threshold at vref, you should require a bit of flare input to bleed 7 more knots and land on the markers at vref-7. The 85 isn't very forgiving and if you’re hitting ground effect at or above vref you will float a lot.
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Hi @rj ! Thanks for providing this space to ask questions.
I wanted to know, what is the SOP you use in terms of bleed air and packs for takeoff and landing? I noticed in multiple YouTube videos that taking off with the APU running is not common at all. These airlines are taking off with only number 4 engine bleed air on, and packs off.
My questions are:
- What is the SOP you use?
- What is the purpose of having the number 4 bleed air running when both packs are off?
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Regardless of packs, at least one air source must be on for take off to power the outflow valves. With the outflow valves pneumatically powered, you’ll have primary and secondary valves fully open so you’re not pressurizing on ground. You can use APU AIR or any single Engine Air, you should not use both at the same time.
If performance allows, we take off with engine airs, on packs on, RECIRC. Take off in FRESH mode with packs powered by engine air is forbidden and if you forget you’ll get high EGTs and you’ll strain the packs.
If performance doesn’t allow an engine air packs on take off, you can use APU air on, packs on, recirc. If your APU is old and can’t handle both packs on, you can take off with APU air on, one pack on, FRESH mode.
If your APU is not serviceable, and performance doesn’t allow a packs on take off, you need to turn on one engine air so that the outflow valves are powered. You can use any engine air but typically engine air 4 is used because that engine air won’t illuminate the AIR SEL ON GROUND on the Central Status Panel.
