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Starting 206L4


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#41 aeroscout

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Posted 30 June 2014 - 22:05

I guess I'm having a hard time with this. I can't find anything that written up about cecos. It seems common knowledge in the world of the internet that cecos are modulated but that doesn't mean it is correct. All I know is that the 2 ceco systems I've used definately had to be modulated. If the systems needed adjustments, then maybe the old guys were ok with that. As far as my experience goes, there's a big difference between the bendix and ceco and that's what I know.

Just to specify, the LR has a standard fuel control that requires a modulated start, and an option for a non modulated start fuel control call the intellistart. The bendix/ceco don't apply to the LRs.



#42 Nearly Retired

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Posted 30 June 2014 - 22:35

Well Dan, as far as the RFM is concerned, there shouldn't be any difference to the pilot.  And I went back to the 206A RFM to see if Bell put a note in there about it. 

 

They didn't.

 

I'd say...and I'm guessing here...that the outfit you worked for probably had the CECO's set up incorrectly for some reason...personal preference perhaps?  In my experience, the CECO and Bendix were interchangeable as far as how the ship started.  The fact that the CECO offers a small amount of adjustability on the TOT during the start doesn't mean you should have to avail yourself of it every time.

 

Then again...I've known pilots who SWEAR that they can "modulate" a Bendix in a B-model.  And I'm here to tell you, after tens of thousands of starts of Bendix-equipped C-20B's over the years...*IF* there is any modulation of the TOT available to the pilot, it is TINY...and probably very FCU-specific...and probably illusory.  They THINK they're affecting the TOT but they're probably not.  I've tried and tried to squeak the throttle back in the various ships I've flown (206B's and Bo-105's), and all I ever get is cut-off. 



#43 iChris

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Posted 01 July 2014 - 03:41

I guess I'm having a hard time with this. I can't find anything that written up about cecos.

 

It seems common knowledge in the world of the internet that cecos are modulated but that doesn't mean it is correct.

 

All I know is that the 2 ceco systems I've used definately had to be modulated. If the systems needed adjustments, then maybe the old guys were ok with that. As far as my experience goes, there's a big difference between the bendix and ceco and that's what I know.

 

It's already documented in the Rolls Royce 250-C20 Operation & Maintenance Manual. The CECO was designed to start without any modulation, if adjusted correctly. It was also designed to allow, unlike the Bendix FCU, a modulated start. Below are excerpts from the Rolls Royce manual. 

 

Set it up correctly and it will start without modulation. Note those two adjustments on the CECO "Start Derichment" & "Light-off Adjust"

 

Click photo to enlarge

ScreenShot2014-07-01at10503AM_zps309a8e9

 

 

Well Dan, as far as the RFM is concerned, there shouldn't be any difference to the pilot.  And I went back to the 206A RFM to see if Bell put a note in there about it. 

 

They didn't.

 

I'd say...and I'm guessing here...that the outfit you worked for probably had the CECO's set up incorrectly for some reason...personal preference perhaps?  In my experience, the CECO and Bendix were interchangeable as far as how the ship started.  The fact that the CECO offers a small amount of adjustability on the TOT during the start doesn't mean you should have to avail yourself of it every time.

 

Then again...I've known pilots who SWEAR that they can "modulate" a Bendix in a B-model.  And I'm here to tell you, after tens of thousands of starts of Bendix-equipped C-20B's over the years...*IF* there is any modulation of the TOT available to the pilot, it is TINY...and probably very FCU-specific...and probably illusory.  They THINK they're affecting the TOT but they're probably not.  I've tried and tried to squeak the throttle back in the various ships I've flown (206B's and Bo-105's), and all I ever get is cut-off. 

 

That's correct...

 

 

Rolls Royce 250-C20 Operation & Maintenance Manual (72-00-00 pg. 62)

 

The 250–C20 Series engines each have two qualified control systems; they are:

 

(1) CECO.

The MC–40 (250–C20, –C20B, –C20J) control system manufactured by the Chandler Evans Control Systems Division of Coltec Industries.

 

(2) Bendix.

The DP–N1 (250–C20) or DP–N2 (250–C20, –C20B, –C20F, –C20J), (control)/AL–AA1 (governor) control system manufactured by the Bendix Engine Controls Division of Allied Signal.

 

C. Starting Modes.

Starting procedures are given for an automatic start mode (CECO or Bendix system) and for a modulated start mode (CECO system only).

 

Automatic Start Mode:

The throttle is advanced directly to the IDLE detent when desired N1 cranking speed is reached.

 

Modulated Start Mode:

The throttle is advanced toward the IDLE detent in increments as required to increase TOT and N1 speed at a steady rate that remains within specified limits.

 

 

 

Rolls Royce 250-C20 Operation & Maintenance Manual (73-20-04 pg. 207)

 

F. Lightoff Adjustment

 

Make the lightoff adjustment by trimming the screw with a 5/64 in. Allen wrench to obtain engine starting fuel and exhaust gas temperature requirements. Turn the screw clockwise to decrease lightoff fuel flow.

 

G. Start Derichment Adjustment

 

The start derichment adjustment can be used to modify the starting fuel flow to improve cold weather starts, stagnated starts, or high altitude starts. Make the adjustment using a 1/4–in. Allen wrench having a 1/2 in. (13 mm) offset (or CECO wrench STD 67181). Turn clockwise (when viewed from end of adjustment screw) to enrich fuel flow for faster and hotter starts. Turn counter–clockwise for leaner fuel flow when starts are too hot. The normal setting is with the travel limiting screw at bottom center. Check the starting peak TOT after each setting until satisfactory starts are made.


Edited by iChris, 01 July 2014 - 04:06.

Regards,

Chris

#44 supergokougt

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Posted 01 July 2014 - 07:04

Wow....Thanks for all the info back and forth. I got to watch and have a few starts explained. Should be starting it myself the next couple days.



#45 iChris

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Posted 03 July 2014 - 02:15

Wow....Thanks for all the info back and forth. I got to watch and have a few starts explained. Should be starting it myself the next couple days.

 

Though we’re talking about a different engine and fuel control unit from that of the Bell 206B, the Bell 206L has also been troublesome to many during the modulation sequence.

 

Rich (hot) starts have been a problem. Causes like weak battery, delayed ignition or premature opening of the throttle are common. However, hot starts due to high fuel flow are normally caused by the fuel control. When you have an over-sensitive and hard to start Bell 206L (250-C30 engine) it could be a fuel control issue. Therefore, we’re back to maintenance and adjustment or even replacement of the fuel control.

 

Some companies have made it a culture of living with marginal aircraft maintenance, if it’s not completely dead, it’s good to go. Or terms like, we’ve been fly it like that for years and no one has a problem with it.

 

When the fuel control is suspected, ask maintenance to make the adjustments. Note the heading in the table below, “Adjustments to Improve Stating

 

Scan-1_zps8af5669c.jpg

Scan-11_zps96d4667e.jpg


Regards,

Chris

#46 Gomer Pylot

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Posted 03 July 2014 - 08:06

Some mechanics are more knowledgeable than others, and some are more receptive to making adjustments than others.  But pilots are the ones who have to make the starts, and shouldn't put up with maladjusted fuel controls.  If it tries to melt every time you start it, then you need to force maintenance to do their job and adjust it properly.  At least two adjustments will probably be needed each year, to compensate for different ambient temps, winter and summer.  Depending on the location, you can probably get by without adjustments if you're willing to live on the edge, but you shouldn't have to.  If the fuel control is adjusted properly, a start is a routine event.  But if not, it can get far more exciting than necessary.  I prefer boredom to terror.


  • 500E and aeroscout like this
Best Regards,

Gomer

#47 Nearly Retired

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Posted 03 July 2014 - 10:27

...said the guy who flies helicopters for a living :-/



#48 Guest_pokey_*

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Posted 03 July 2014 - 10:43

I really hate to say this, and I know it is a cheep shot, (but I have been the victim also of them by him)

 

if it doesn't start the 1st time? there must be a bug in the system  :P



#49 aeroscout

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Posted 03 July 2014 - 13:47

I really hate to say this, and I know it is a cheep shot, (but I have been the victim also of them by him)

 

if it doesn't start the 1st time? there must be a bug in the system  :P

It's a lighthearted friendly jest, at the worst. That won't keep someone from blowing it up into the unimaginable. 



#50 PanzerKop1973

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Posted 23 December 2018 - 22:16

Hello everybody!
Could any pilot in this forum provide me a Bell 206 Long Ranger checklist file or indicate where could I find one to download it please?
Thanks in advance from Santiago de Chile.
arayaparodi@hotmail.com




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