King Air B200 Operational Questions

[Covey582]

King Air Drivers,
I'm new to the B200, flying a ship with a serial # over 1770, which affects the POH procedures.
I'm trying to understand the "why" behind ...
1) On start the POH does not require the first generator to be put on line, then turned off for the second start, and then put back on line. I'm trying to understand the reason for this (not just that the POH directs it) ... versus the "old" way (pre serial # 1443) of cycling that generator on-off-on.
2) On start, the POH directs first selecting Low Idle on the first-engine-started, then HIGH Idle on that engine, before that engine start switch is turned off. Then, after the second engine is started, the POH calls for putting the condition lever of the first-engine-started back to Low Idle. Again, it's in the POH, but I would like to understand why the Low-High-Low use of the condition lever on the first engine started.
Finally, ...........
3) The POH does not call for the use of Auto Feather throughout a flight, from takeoff to landing, though I've seen it used that way. I'd like to understand why Auto Feather shouldn't be used for the entire flight?
Thanks in advance,
Covey582

[MyNameIsIs]

Cannot give a good explanation of #1 unfortunately.
However, the "off then on" is what is called a GENERATOR ASSISTED START. Leaving the other generator on for the engine start is called a CROSS GENERATOR START.

I think Cross Gen starts are mandatory for KingAir models with a "five bus" electrical system and some of the latest B200s. I'm not up to date but you may have the electrical system that effectively dictates cross gen starts.

Regardless of starting method, one of your biggest concerns after starting the 2nd engine is your current limiters.
Once you have started the 2nd engine, BEFORE you turn the 2nd generator online, go up to your load meters and press the buttons to get volts. Both should read 28v (which is the 1st gen output). If you have a blown current limiter, the voltage will read lower on the opposite side (it will read battery volts).
The biggest danger with blowing the Right current limiter is that your gear motor runs off the R Gen Bus. If on takeoff your R engine or R Gen fails before gear retraction, you aint getting them up!



#2
Increasing to Hi Idle assists battery recharging for the 2nd start. Also regardless of whether you do a gen assist or cross gen, being at hi idle means when the other engines starter is selected, the load placed on the operating generator will not reduce it's engine speed below the idle limit.

After the 2nd engine has started, reducing the idle of the 1st engine is determined by things like your electrical load (ie aircon, heater) to once again ensure the engine doesn't slow down below limits.
You may also need to have the condition levers above Lo Idle to keep the idle ITT limit in check. It sounds counter-intuitive to increase your engine speed if your idle ITT is pushing thru it's limit, but increasing the engine speed means increased airflow through the engine and a cooler ITT. I've rarely seen this though.



#3
Not using autofeather in cruise, for example, will mean that if the engine fails it will windmill, thus allowing the use of the windmilling start procedure - which is much better than compared to using the starter for EFIS equipped aircraft.

Autofeather is primarily designed for helping you out in critical flight phases. Cruise, when you have time, speed and altitude, you can manage a failure very easily without the system doing it for you. But if you want to leave it on, you can.

On early 3 blade KingAirs, autofeather was an option. 4 bladers require the autofeather for takeoff, its a no-go item if it doesn't work.
I'm not overly keen having to manually feather a 4-blader on takeoff, especially using balanced field procedures- they bite you hard if they do not feather, hence autofeather is mandatory.

[MungoP]

I'm going to be cheeky here and add a further Q...
Why does the POH stipulate that fuel transfer cannot be carried out except for when one engine is inoperable ?
On two occasions during my time in Africa I've had to transfer fuel with both engines running and it worked just fine..
While at the Beech factory in Wichita I asked around and no one could give me an answer.

[Tinstaafl]

I've wondered the same. It also applies to Piper PA31s. It could be a system limitation that, under a certain set of circumstances, doesn't guarantee the fuel supply. Or, pragmatically, the manufacturer may not have bothered testing that ability during certification.

For the orginial question re start:

Older Kingairs have 300 amp current limiters - essentially a big fuse - in the electrical path between each generator's buss and the other engine's starter/generator. During start the starter pulls around 1000 amps which reduces rapidly after ignition. Delaying the use of the 1st engine's generator when starting the second reduces the chance of blowing the current limiter. Newer Kingairs have a different electrical system that removes that limitation. Can't remember how, other than it's a 5 buss system, as was written in an earlier post.

[ahramin]

1) The gen assisted (on off on) method was developed to maximize gen use during start without blowing current limiters. BB1770 has gen ties rather than current limiters so no need to turn the offside gen off for the initial starter cranking.

2) High idle to have the generator turning at a higher RPM, reducing torque demand from the generator on the engine. Basically it's easier on everything.

3) The reason for an autofeather system is to help deal with an engine failure in low speed / high power setting situations where you are close to your VMC and loss of control becomes a danger. This doesn't apply to cruise flight. As stated, if you are going to attempt a relight you are far better off with the engine windmilling.

[MyNameIsIs]

The only explanation I can come up with in relation to fuel transfer is more of an arse-covering measure by Beechcraft.

You can have up to a 1000lb fuel imbalance per side (wing lockers will reduce this figure, something like 700lbs imbalance?), so a few hundred pounds imbalance whilst all engines operating is no big deal. I've previously flown one about 400lbs out of balance. Nothing drastic.

Unless you/someone else are incompetent in refuelling you are never going to be in a situation getting close to being out of balance.

I highly suspect the system wasn't designed to transfer fuel, um, "normally" but rather designed solely for the one-inop scenario, so my best guess is that they just tell you it's a limitation.



On a similar fuel topic, here's a fun thing to think about.
Why must the main tanks be full before putting fuel into the aux tanks? It is another unexplained limitation from the books.

Think about how the fuel system works. Can you remember it???
This is what I've come up with - keep in mind its just my theory!

It's all to do with the motive flow. One needs fuel in the mains (and fuel in the aux to open up the motive flow valve) to be sent through the jet pump in the aux tank- the jet pump is just a venturi. This fuel which has originated in the main tank flowing thru the jet pump creates motive flow and thus "sucks" fuel from the aux tank.

You will obviously need a certain minimum amount of fuel in the main tank to be able to provide enough motive flow and draw out a full tank of aux fuel- so far I have not been able to determine just how much though.
One way to think about this is in the extreme. Fill up your auxies and leave the mains empty. You aint going anywhere! The auxies do not supply fuel to the FCU "directly", you need main tank fuel to provide the motive flow.

[LASJayhawk]

200 aux tanks transfer into the nacelle tank, just like the wing tanks. I kinda think the requirement to fuel the mains first of a 200 is to prevent someone from filling the aux tanks full, but not the wings. This could cause a problem with the weight distribution in the wings.

When you start a 200 full of fuel, it starts transferring from the aux tanks into the nacelle, when the aux tanks run out the pump shuts off and the wing tanks gravity feed the nacelle.

If you look at the gross weight increase kit from Raisbeck for the 90's, it adds lead weights to the outboard wing to accommodate the increased weight over the center section.

Note on a C90, you have to fill the nacelle tanks before the wing tanks. If you do the wings first, they will gravity feed the nacelles. By the time you fill the nacelles, your wings may well be 50-100 pounds less than full.

[MyNameIsIs]

Jayhawk, in the KA200 the nacelle tank is considered part of the main tank system. I don't know about newer models, but in the early 90 series KA the Nacelle was a separate tank in the system altogether. 90s referred to "nacelle" and "wing" tank systems separately if I remember correctly. 200 refers to "main" and "aux" systems.

Yes the 200 does have the tank in the nacelle, but fuel contained in there is considered mains fuel- don't believe me? Grab a manual and add up the capacities for all the box sections, wet wing section, nacelle, leading edge tanks etc and you might find that it equals the book figure for the Main system :ok:



The jet pump in the 200 aux tank is not an electrically driven pump. The electric side of things is effectively just a sensor which will see if there is fuel in the aux and if there is it will open the motive flow valve. When the aux tank empties, the motive flow valve closes and stops fuel from going through the jet pump- it does not "shut off" the pump.


I kinda think the requirement to fuel the mains first of a 200 is to prevent someone from filling the aux tanks full, but not the wings. This could cause a problem with the weight distribution in the wings.

I reckon you are correct with your first sentence, but I doubt the reason is for balance reasons.

I wouldn't think that 57 gallons in the nacelle section only (no more in the rest of the mains) would be able to draw out 79 gallons from the aux tank via a venturi! Hence why mains must be full first!

[avionimc]

"The King Air Book" by Tom Clements will give a thorough explanation to all your questions, and much more. A must read book for a thoughtful King Air pilot.

King Air Tips and KLN-90 Training (http://www.flightreview.net/)

e-booK:

The King Air Book by Tom Clements (eBook) - Lulu (http://www.lulu.com/us/en/shop/tom-clements/the-king-air-book/ebook/product-17396052.html)

[LASJayhawk]

MyName... Yes I understand the difference between the 90's and the 200's. I mentioned it in passing if some 90 driver comes by and thinks a KA is a KA.

Damn, I'm going to have to transcribe this all by hand. It's a major PITA to print the iml from an ipad, so I will type (i hope without many typos) From chaper 28-20-00 of the super king air 200 (aka B200) Maintenance manual Rev

28-20-00 page 2 rev Nov 1/07 (revision date of the page in the current manual)

Jet Transfer Pumps:

A jet pump mounted directly (snip)

Once the motive flow valve has opened, the jet transfer pump will continue to transfer fuel from the auxiliary tank to the nacelle tank for as long as either the engine-driven boost pump or the electrical standby boost pump is operative and there is fuel in the auxiliary tank. An overflow line (snip again)

No mention of requiring fuel in the mains, and that is what makes me guess it is loading in the wings for lack of a better explanation.

It goes on to explain that the jet pump won't be hurt running dry, but could draw moisture into the fuel system if not made to shutdown.

Taken from the super King Air 200 series maintenance manual P/N 101-590010-19, Revision C13, May 1/13

IMHO: it may not matter as much in a civil KA that is grossed at 12,500...but the military ones IIRC are 14,500.

Covey582, sorry for hijacking your thread. :oh: I know the perfect person to answer your questions, but he doesn't hang out on PPRuNe, mainly BeechTalk. I'll either get him to sign up, or I'll email the questions and post the answer.

[LASJayhawk]

avionimc's post may insure the perfect person I had in mind will join the board. :E

[MungoP]

Unless you/someone else are incompetent in refueling you are never going to be in a situation getting close to being out of balance.

Welcome to Africa..
Had I not been able to transfer fuel on the subsequent flights I'd have run one side dry.

[lilflyboy262...2]

Hope nobody minds that I have dragged this up from the dead.
But the Aux tank limitation as per what I read from a Beechcraft Rep is this.

Good Morning All,

I too, am late to this party and thought I would offer official Beechcraft comments to this discussion regarding fueling procedures on the King Air B200 and B300. Because this question has come up numerous times at King Air Technical Support through the years, we published this article in the 2007-02 King Air Communiqué and I hope that it helps.

King Air Fueling Procedures ATA 28
200/300 Series
Technical Support receives questions regarding the fueling procedures for the King Air 200 and 300 series aircraft. The King Air Pilot’s Operating Handbook has the following warning, although the wording may vary from POH to POH, they generally say the same thing:

Warning
Do not fill the auxiliary tanks unless the main tanks are full.

There are some technical, operational and structural reasons for this warning.
• If you were to fill the auxiliary tanks only and fill the airplane with people and cargo, the
total load would be concentrated in the fuselage and the center section. This is not a
desirable condition since the wings would not be “loaded”. By flying with the wings full of
fuel, the fuel load would act as a shock absorber to the loads exerted through out the
structure of the wings. The total load is also spread across the whole wing spar system.
• The King Air fuel system will empty the auxiliary tanks first to keep the load spread
across the spar system.

Doug Bowlsby
Pacific Northwest Propeller Field Representative
Beechcraft Corp

Hope that answers that question :ok:

[f2000]

I suggest you buy Tom Clements King Air book. All this will be explained, he is a boffin on all the King Air models going back to the first KA produced.