NTS Tests

[av8r]

NTS Tests:

I would like to pose some questions concerning the performance of mandatory/recommended NTS tests by current/past turbine operators.

There are five tests that can be performed using the NTS system to evaluate the proper operation of engine components, they are:
 
1- NTS Lockout Valve Test: This test evaluates/confirms the performance of the NTS Lockout system.
2- Feather Valve Manual Test: This test confirms the connection between the Condition Lever (CL) and the mechanical side of the feather valve.
3- NTS Functional Test: Light out upon starter engagement during start sequence.
4- NTS Check Valve Test: Confirms reseating of the NTS Check Valve after an NTS test has been performed during engine start.
5- Supplemental NTS Test: May reveal a loss of prop governor oil pressure to the NTS system.

Questions:
1- Do you perform all five test or do you limit the number of tests you perform?
2- Do you leave it to maintenance to perform these tests?
3- At what frequency do you perform the tests?
4- Do you feel that these tests enhance you knowledge of the operational characteristics of you aircraft?
5- Do you feel that all five test should be performed as recommended by Commander and by Honeywell? If so why?

Your input is appreciated.

[SKYFLYER]

This may help shine some logic on your query... http://www.flightlevelsonline.com/issues/fall12/article/from-the-shop-floor.html
As for frequency the jetprops (695A, 695B) the AFTER START/BEFORE TAXI states NTS check valves TEST FIRST FLIGHT OF THE DAY.

[donv]

Depends on whether it's a 690 or a Jetprop (840/980/1000). In a 690, I do the functional and check valve on the first flight of the day. In a Jetprop, I do them on all starts.

Why? Because it's a bit of a hassle to do the check in a 690, and conversely it's easier (from a flow perspective) to do it than to not do it in a Jetprop.

I never do the other checks... maybe I shouldn't admit that.

[MikeDelta]

Why do you find it a hassle on a 690? Once you know how its done, it's fairly simple. Unless I'm doing it wrong... 

[donv]

It is fairly simple, if you have three hands...

The issue in a 690 is you have to hold the momentary NTS switch down with one hand, actuate the starter with the other hand, and use the third hand to guard the condition lever.

It's not that bad, but in the Jetprops, they made it so that the NTS test switch stays pressed until you turn it off, eliminating the need to hold it. So each start, you flip the torque limiter off and turn the NTS test on (right next to each other), start, and once the engine is running flip them back to the middle position (torque limiter on, NTS test off).

[MikeDelta]

Not sure what you are flying but I fly the straight 690.

What I do (first flight of the day):

- For start, I depress NTS button while in AIR START, light comes on, switch to GND START, light goes off. Then move hand to condition lever. No third hand required.

- After both started, in the locks, condition levers forward, depress NTS both sides, no lights. No third hand.

- After that, full throttle for governer check.

- Flight idle again, condition to 85, full reverse one by one, wait for the unlock. Condition low, ground idle. Humming nicely.

All done with 2 hands. All checks done?

Am I doing it wrong? 

[donv]

That's how you do it in a 690. It's just not quite as easy as having the switch stay in NTS test during the start without you having to hold it.

Fly a Jetprop sometime, and you'll understand what I'm talking about. Thus, I do it on pretty much every start (except if I'm just taxiing the airplane).

[MikeDelta]

Aha gotcha.

[Bruce Byerly]

Not sure what you are flying but I fly the straight 690.

What I do (first flight of the day):

- For start, I depress NTS button while in AIR START, light comes on, switch to GND START, light goes off. Then move hand to condition lever. No third hand required.

- After both started, in the locks, condition levers forward, depress NTS both sides, no lights. No third hand.

- After that, full throttle for governer check.

- Flight idle again, condition to 85, full reverse one by one, wait for the unlock. Condition low, ground idle. Humming nicely.

All done with 2 hands. All checks done?

Am I doing it wrong? 

I believe over speed governor checks have been recommended by Honeywell to be completed after maintenance or very much less frequently than everyday.  I believe this has been the recommendation for many years now.  I was taught this at the Honeywel 331 school in Phoenix anyway.

The 3 hands are required when you want to hit the starter at the same time the primer is depressed (-10T) while holding the condition lever on top of the gate and the NTS switch at the same time you are looking for the TQ limiter in case you need that switch.  Very much a 3 handed operation in those -10 690's to do it right but it's really not that bad 

Also, I have found and had some of the top engine techs endorse unlocking gently in ground idle for much less drama.  I've always done this and never had a problem.

But I may be doing it wrong too.  Who is the OP - is that you Jerry?   

[donv]

In a 690 with Bendix fuel controls, all you need to do to unlock the props is pull the power levers back toward reverse until the beta lights blink.

I always found the Jetprops to be harder to unlock. In my 980, I leave the condition levers in low and pull each power lever back until the EGT spikes (which, as was pointed out at my recurrent training a few years back, happens because the SRLs activate at 80%-- duh!). So I guess that's the same thing as pulling them back until 80%...

I don't do the overspeed governor check except after maintenance. I do the NTS check valve check when I line up on the runway, after going to high RPM. That was another thing which came out of a recurrent-- if you do the NTS check on start, you need to do the check valve check.

I never go to high RPM until lined up on the runway.

[MikeDelta]

Not sure what you are flying but I fly the straight 690.

What I do (first flight of the day):

- For start, I depress NTS button while in AIR START, light comes on, switch to GND START, light goes off. Then move hand to condition lever. No third hand required.

- After both started, in the locks, condition levers forward, depress NTS both sides, no lights. No third hand.

- After that, full throttle for governer check.

- Flight idle again, condition to 85, full reverse one by one, wait for the unlock. Condition low, ground idle. Humming nicely.

All done with 2 hands. All checks done?

Am I doing it wrong? 

I believe over speed governor checks have been recommended by Honeywell to be completed after maintenance or very much less frequently than everyday.  I believe this has been the recommendation for many years now.  I was taught this at the Honeywel 331 school in Phoenix anyway.

The 3 hands are required when you want to hit the starter at the same time the primer is depressed (-10T) while holding the condition lever on top of the gate and the NTS switch at the same time you are looking for the TQ limiter in case you need that switch.  Very much a 3 handed operation in those -10 690's to do it right but it's really not that bad 

Also, I have found and had some of the top engine techs endorse unlocking gently in ground idle for much less drama.  I've always done this and never had a problem.

But I may be doing it wrong too.  Who is the OP - is that you Jerry?

Yeah I suppose you are right. No sense in doing it daily really.

Can it damage something however? Or is it more an unnecessary wear issue?

[donv]

It's certainly unpleasant for anyone on the same ramp as you!