Question for Q drivers

[loopa]

I was just wondering, what's the reason for the spoilers being deployed just before take off on the Q400? The first time I noticed it I wanted to jump on the radio and let the flight crew know their spoilers were left up

Just curious if anyone can shed some light on this.

Thanks!

[whiteguy]

I was just wondering, what's the reason for the spoilers being deployed just before take off on the Q400? The first time I noticed it I wanted to jump on the radio and let the flight crew know their spoilers were left up

Just curious if anyone can shed some light on this.

Thanks!

Same as the 100s...

Basically they get armed with flight/taxi switch and drop once the power levers are advanced.

[loopa]

Oh ok thanks whiteguy!

Would you by chance happen to know the actual reason why armed means they deploy before takeoff?

I imagine there are way too many warning messages that go off should the Ground Spoilers not stow for takeoff, I just can't logically make out why they would be deployed before such an important phase of flight.

[whiteguy]

Oh ok thanks whiteguy!

Would you by chance happen to know the actual reason why armed means they deploy before takeoff?

I imagine there are way too many warning messages that go off should the Ground Spoilers not stow for takeoff, I just can't logically make out why they would be deployed before such an important phase of flight.

For the 100 it's just the design. Once the power levers are advanced the spoilers drop and they work with the ailerons for roll control. If the switch is not selected to flight and the power levers are advanced the spoilers will arm and deploy themselves then drop.

On landing, once you have weight on wheels and power levers towards flight idle, the spoilers will deploy as lift dumping devices.

Not sure how similar the Q400 is to the 100 system but I'll find out once our Q400s arrive in a few months. .

[vanishing point]

Another question for the Q drivers: is it SOP not to taxi with one engine in feather like we do on the classic or is it a limitation imposed by Bombardier?

What fuel burns do you have during taxi?

[volez]

Hey Loopa,

Looks strange, doesn't it ?

When we re about to line up we switch our flight/taxi switch to flight. Once it's on flight, the spoilers will retract as soon as we go past a preset power lever angle and deploy only with weight on wheels once we get back to this preset power lever angle. The reason being is the arming of spoilers for landing before we takeoff. Therefore, we do not touch this switch at all between the before TO and the after landing phase.

2 to 300 lbs are accounted for taxi fuel burn depending on the airport.

[vanishing point]

The OFP states the planned taxi burn but what do you guys actually see on the gauges with the props at min rpm?

The -300 typically shows ~300/hr at min and ~150/hr in feather. The -100's were a bit less than that, IIRC.

What's the deal with the "one-in-feather" taxi on the -400?

[Blue Yonder]

In g/s, they told us it produced too much torque on the nose wheel to taxi with one in feather.

Blue

[Maxpwr]

Next AOM from Bombardier will have single engine taxi procedures apparently.

[Beach 200]

You can taxi a Q400 with one in feather but no operator will do it. Simple reason is cost. Typical fuel savings with one in feather on the Dash 8 100 and 300 are good. Even better on the Q400, but due to the added torque and strain on the nose gear, the cost of repair and maintenance out weighs the fuel savings substantially on the Q. So hence why it won't be done!

Spoiler reason, well the Q is like the dash 8 classic due to being designed from an old type certificate. I'm sure Bombardier could have designed the spoilers more like modern aircraft but since the Classic had GROUND spoilers also, which are worked into the STOL design of the plane, the Q was just stuck with...well as everyone explained above multiple times. I still think the Q should have gotten its own type certificate. Dash 9 or something.....

[BingBong]

FADEC has the fuel burn around 300 lbs/hr regardless of
Being in feather or at Disc on the ground.

[Canoehead]

Q400 single engine taxi (ie: #2 shut down) is coming. European operators are doing it already, and it equals a fuel savings of about 13kg per leg. It will start as a taxi-in operation initially, eventually taxi-out also will be on one.

Also coming soon... a better chance at getting on top of the weather

[aileron]

You can taxi a Q400 with one in feather but no operator will do it. Simple reason is cost. Typical fuel savings with one in feather on the Dash 8 100 and 300 are good. Even better on the Q400, but due to the added torque and strain on the nose gear, the cost of repair and maintenance out weighs the fuel savings substantially on the Q. So hence why it won't be done!
...

No, the reason is that BA did not have in place an AOM procedure. The real issue is the lack of an energized #1 Hydraulic system, ergo no brakes. The trials have been completed with FlyBe and in 300 days of tests (75,000 cycles) there has been insignificant tire and landing gear wear. The no.2 engine is started and the STBY HYD pump is energized, thereby providing hydraulic brake pressure.

The issues that have cropped up is: Not selecting Autofeather after the no.1 engine is started, prior to T/O, and Not selecting or deselecting the STBY HYD pump at the gate (leaving or arriving respectively).

Overall they have saved 40lbs of fuel per sector. Huge savings for a fleet...

[Beach 200]

You can taxi a Q400 with one in feather but no operator will do it. Simple reason is cost. Typical fuel savings with one in feather on the Dash 8 100 and 300 are good. Even better on the Q400, but due to the added torque and strain on the nose gear, the cost of repair and maintenance out weighs the fuel savings substantially on the Q. So hence why it won't be done!
...

No, the reason is that BA did not have in place an AOM procedure. The real issue is the lack of an energized #1 Hydraulic system, ergo no brakes. The trials have been completed with FlyBe and in 300 days of tests (75,000 cycles) there has been insignificant tire and landing gear wear. The no.2 engine is started and the STBY HYD pump is energized, thereby providing hydraulic brake pressure.

The issues that have cropped up is: Not selecting Autofeather after the no.1 engine is started, prior to T/O, and Not selecting or deselecting the STBY HYD pump at the gate (leaving or arriving respectively).

Overall they have saved 40lbs of fuel per sector. Huge savings for a fleet...

Well your somewhat correct. In all procedures the Sty Hyd Press is energized on both systems after start with PTU selected on. Viola you have brake press in #1 System. This happened to a Porter aircraft in YHZ some years ago. Crew started #2 to taxi in. But obviously had no brakes. Although had the crew done after start checks the stby press would have been selected with the PTU and the whole event could of been avoided.
Yes you can taxi in one off or feathered, however as I said landing gear strain costs out weigh the benefits....actually you said that too.

[vanishing point]

Single-engine taxi and "one-feathered" are two different things.

I don't know of any operator who taxi's with a Dash engine shut down.

I suspected it was a torque issue with the 400.

Thanks for the info.

[Canoehead]

http://youtu.be/pkdQEmo1Fr4

I stand corrected, it's #1 shut down (makes sense). I've also seen flight deck video of their procedure.

It is coming to Jazz, providing the risk analysis is favourable for it (and I'm certain the accountants will win).

Piedmont was (maybe still) doing it with their -100's/-200's. Shutdown, not just feathered.
Seen it many times here in the east.

[Simikin]

I don't want to comment on what procedure the operators are trying to have approved because I don't know anything about that. But for some input not from a Q driver, but from a Q wrencher:

The Power Transfer Unit uses #1 Hydraulic system flow to turn a pump that creates pressure in the #2 system. The PTU by design cannot reverse and power the #1 system from the #2 side. There is only 1 Standby pump and it provides pressure in the #1 system, normally energized by the #2 engine AC generator.
The SPU would be the only source of #1 hydraulics if the #1 engine was shut down during taxi.
The PTU would be the only source of #2 hydraulics if the #2 engine was shut down during taxi.

With toe brakes powered by #1, and Steering and Park/Emergency brakes powered by #2, you would lose system redundancy regardless of which engine was shut down during taxi. By shutting down #1 engine you would then rely entirely on the electric SPU for toe brakes.
Neither the APU nor the #3 Standby hydraulic system can help with these systems.

I'm not trying to be a big instructor here, just hoping that everyone can grasp the issues that come up when faced with a single engine taxi. Currently there are no approved single engine taxi procedures for Maintenance because of this loss of redundancy.
It's obvious that there are many policies that differ between Flight Crew and Maintenance.

[vanishing point]

Did Bombardier redesign the PTU for use on the -400?

Reason I ask is, on the -100/-300, the sole purpose of the PTU is allow raising and lowering the landing gear should the #2 engine fail. It does not power the #2 hydraulic system.

[Simikin]

They did.
I can't explain the design logic as to why they made the changes the way they did, but they got rid of the #2 Electric SPU and in it's place use the PTU as the alternate source to the Engine Driven Pump for the #2 side.
You can hear it whining and grunting in the mid-cabin area during taxi.

[leftoftrack]

What are typical hourly burns? What is OEW? MTOW? MLW? Can you haul full pax and full baggage comp?

Thanks