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[REPORTED] Warning pushlights


iFoxRomeo
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Some of the warning pushlights in the sabre don´t function properly.

Its only a minor thing.

 

 

Fox

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Oh.. sorry Zabuza. Didn´t see your thread. Can a mod merge them please.

 

I've got this answers from developer:

 

- Hydraulic system lamp test should not work

- Empty drop tanks lamp test will work only if switch is in OUTBD ON position

 

But why? The pushbutton is there to check if the lamp inside is working, not if the whole system behind the button is functioning. Thats the whole purpose of the push function. E.g. the fire test is triggered by the separate switch. But first you check if the lamp inside the pushbutton is functioning by pressing it.

 

Fox

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I don't why it is designed this way, but it is how it works according to TO. Maybe there were some reasons to do so.

 

I know I can be picky.

 

I´m sorry cofcorpse, but this is not correct.

 

According to the T.O. 1F-86F-1 :

 

attachment.php?attachmentid=127618&stc=1&d=1447763415

 

attachment.php?attachmentid=127619&stc=1&d=1447763415

 

These lights are push-to-test types. The whole purpose of this push function is to test the lightbulb if it is ok or burnt-out. For this push-to-test function it is irrelevant what system these lights monitor.

 

Fox

948994042_page36.PNG.b3fee4333fb176e411c88a5eb7b3cc81.PNG

1651526357_page83.thumb.PNG.5daebbd476626e42b779a706a6795078.PNG

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  • ED Team

7968143.png

As you can see here, test function (black triangle in circle) will work, only if we have positive contact - so we need switch in OUTBD ON position

 

Maybe the reason of such function is that you need this light only if you have outboard tanks installed. This prevents from false function of this light. I dob't know, I can only guess :music_whistling:


Edited by cofcorpse
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Thanks, that makes some sense.

 

With fuel in the outboard tanks and the selector to 'OUTBD ON & JETT', the light wouldn't be on, but you could push to test the bulb hadn't gone.

 

 

 

What about the 'Flight Control Alternate - On' warning light?

 

Do you have the circuit diagram for that one? Seems strange there was no way to test it even though it was a push to test type switch.

 

Also shouldn't the light come on when the 'Alternate Hydraulic Emergency Override Handle' is pulled? (It currently doesn't).

 

The diagram in the F-86F Flight Manual suggests it should.

 

Flt_Ctl_Warn_0001.jpg

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7968143.png

As you can see here, test function (black triangle in circle) will work, only if we have positive contact - so we need switch in OUTBD ON position

 

Maybe the reason of such function is that you need this light only if you have outboard tanks installed. This prevents from false function of this light. I dob't know, I can only guess :music_whistling:

 

Thank you very much cofcorpse!

 

That is a really odd decision by the constructors.

 

Fox

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Thanks, that makes some sense.

 

With fuel in the outboard tanks and the selector to 'OUTBD ON & JETT', the light wouldn't be on, but you could push to test the bulb hadn't gone.

 

 

 

What about the 'Flight Control Alternate - On' warning light?

 

Do you have the circuit diagram for that one? Seems strange there was no way to test it even though it was a push to test type switch.

 

Also shouldn't the light come on when the 'Alternate Hydraulic Emergency Override Handle' is pulled? (It currently doesn't).

 

The diagram in the F-86F Flight Manual suggests it should.

 

img removed

 

I have to wrap my head around these wiring diagrams. The lamp is on the right side and middle.

 

attachment.php?attachmentid=127654&stc=1&d=1447784123

 

attachment.php?attachmentid=127655&stc=1&d=1447784123

 

Fox

145306541_page96.thumb.PNG.ff337f68dd02a11b6da17628b7f0193c.PNG

33199969_page98.thumb.PNG.cd37e00be0ccdd1b0874cde18bd4ab0a.PNG

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Ok many thanks for confirming the 'Flight Control Alternate - On' warning light correctly doesn't have 'push to test' functionality.

 

 

I'm still confused why the 'Flight Control Alternate - On' warning light does not come on when the 'Alternate Hydraulic Emergency Override Handle' is pulled.

 

Both the manual and the circuit diagram suggest it should be on "whenever the flight control alternate hydraulic system is operating", regardless of whether the switch over was automatic, or manually selected using either the electrical switch or the override handle.

 

Flight_Control_Alternate-On.jpg

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  • ED Team
I'm still confused why the 'Flight Control Alternate - On' warning light does not come on when the 'Alternate Hydraulic Emergency Override Handle' is pulled.

 

When the 'Alternate Hydraulic Emergency Override Handle' is pulled light will come on only if there is no pressure in normal hydraulic system. So everything seems ok to me :thumbup:

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Um, that's not how I'm reading it at all.

 

The light isn't indicating low pressure in the Normal Hydraulic System, but rather that the Alternate Hydraulic System is operating. Yes the system will automatically switch over to the alternate system if the pressure is low in the normal, but the alternate system can also be activated by either the electrical switch or the emergency handle. The light just shows it's in operation.

 

Pulling the handle should switch over to the alternate system regardless of system pressure.

 

Flight_Control_Alternate-On_001.jpg

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  • 3 years later...

Just got the F-86F and was immediately irked by the non-functional 'Push-to-Test' of the ALTERNATE ON lamp.

 

tJQOlqc.png

 

I've read this thread and looked at the schematics. Why did North American bother drawing all three lamp connections if the push test is non functional? Looking at the schematics I think Push-to-Test should work in NORMAL hydraulic boost mode. It also should work (except inverted, lamp goes out when pushed) in ALTERNATE hydraulic boost mode. Refer fig 2-26 "f-86f maintenance handbook". ALTERNATE ON lamp pin numbers according to schematics (symbol chart):

 

CvbbWWw.png

 

Two situations, NORMAL and ALTERNATE boost mode.

  • NORMAL mode.
    Pin 3 is 24/28V (connected to both battery and primary bus) and pin 1 is grounded through the ALTERNATE SYSTEM TRANSFER VALVE operating coil and through the AUTOMATIC RETURN-TO-NORMAL PRESSURE SWITCH. The paired pressure switches will connect to ground as long as the alternate system pressure is nominal (high). A small question mark here. I assume the solenoid coil DC resistance of the ALTERNATE SYSTEM TRANSFER VALVE is low enough (zero?) for the lamp to shine. By pressing Push-to-Test (connecting pin 3) one actually sends current through the ALTERNATE SYSTEM TRANSFER VALVE going through the lamp (pin 3 to pin 1). But it's a safe bet, I think, that the current limiting resistor in the lamp reduces current to a trickle, not enough to move the Transfer Valve (but the lamp will shine). Searching the internet for DC coil resistance:
    What happen if DC current passes through a coil and why ?
     
    Nothing special should happen. If we neglect the proper impedance of the wire, the theoretical impedance of the coil is proportional to the frequency : Zcoil = j.L.ω with ω = 2.π.f and L the inductance of the coil.
    If the current is DC then f = 0 and consequently Zcoil = 0, the coil acts only as a wire.
    https://www.researchgate.net/post/What_happen_if_DC_current_passes_through_a_coil_and_why
    The only question for me is: Will the lamp shine if put in series with the Transfer Valve solenoid coil to ground? Yes, I think it will.
     
    Ed/add: Think about this. Think about how much current (a lot) the heavy operating hydraulics solenoid coil swallows then 28 V is applied to it. Think about putting a lamp in series with this. Think the lamp would not shine? I don't know what kind of lamp the push lamp is/was but I'm pretty sure it would be current limiting. The lamp would limit the current to not burn up itself. P = U x I. Imagine lamp is 3 W. 3 = 28V x I, I = 107 mA. If the coil was 20 W it would draw 714 mA.
     

  • ALTERNATE mode.
    Pin 2 is ground (through the AUTOMATIC RETURN-TO-NORMAL PRESSURE SWITCH, pin 1 is 24/28V making the lamp shine. When pushed, pin 3 (24/28V) gets connected. Now the lamp gets 24/28 V in both ends (pin 3 and pin 1) and should go dark.

Neither of those things happen in the simulation.

Fig 2-26 (page 96, pdf 102) "f-86f maintenance handbook" and fig 1-24 (page 1-36, pdf 46) "F-86F Flt Manual + perf data". Both uploaded by drPhibes.

WH6kw7y.png

P8m1L2W.png

~

 

Here's the long version (not kidding), where I recounts things I figured out before arriving at summation above. Note, throughout this text I bold (and follow capitalization of) direct schematics quotes (all quotes from fig 2-26 unless otherwise specified).

 

Everything can be read from the figure 2-26 schematics but it was very helpful looking at the overview (figure 1-24) to get the big picture. Fig. 1-24 makes it clear that the default (spring loaded) unoperated state of the two solenoid TRANSFER VALVEs is NORMAL SYSTEM open and ALTERNATE SYSTEM closed. One can also see that a single electric line energizes or de-energizes both TRANSFER VALVEs and the ALTERNATE TO lamp simultaneously.

 

Ed/add: Note, the "single line" is a little different in reality on schematic 2-26. Both Transfer Valves and the lamp are hard tied together, but this is on the side that only ever gets grounded (by the AUTOMATIC RETURN-TO-NORMAL PRESSURE SWITCH), not energized. The lamp and both Transfer Valves are also connected on the positive side except the Normal Transfer Valve coil can be broken up by a switch (FLIGHT CONTROL) and then reconnected by a second switch (NORMAL SYSTEM PRESSURE SWITCHES). Nominally the Normal Transfer Valve positive side coil is connected to the lamps and the Alternate Transfer Valve coil positive side except for very brief periods of transition between different switch configurations. The bigger point the "single line" conveys is that nominally both Transfer valves acts in concert, they are either both actuated or both are not actuated.

 

I needed to look up some terms for figure 1-24.

 

GYv8AXS.png

A check valve, clack valve, non-return valve, reflux valve, retention valve or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction.

https://en.wikipedia.org/wiki/Check_valve

A pressure sensor is a device for pressure measurement of gases or liquids ... A pressure sensor usually acts as a transducer; it generates a signal as a function of the pressure imposed. For the purposes of this article, such a signal is electrical ... Pressure sensors can alternatively be called pressure transducers, pressure transmitters ...

https://en.wikipedia.org/wiki/Pressure_sensor

A pressure switch is a form of switch that closes an electrical contact when a certain set fluid pressure has been reached on its input. The switch may be designed to make contact either on pressure rise or on pressure fall.

https://en.wikipedia.org/wiki/Pressure_switch

I made assumptions about which pressure switch operates on pressure rise and which operates on pressure fall. This probably can be read on the schematics (with a magnifying glass:(). There's three pressure switches. Top to bottom (figure 1-24, names from figure 2-26 unless otherwise noted):

 

  • ALTERNATE PUMP CONTROL PRESSURE SWITCH feedbacks to ALTERNATE SYSTEM PUMP (on fig 1-24 named ELECTRIC-MOTOR-DRIVEN ALTERNATE PUMP). This switch closes on alternate system pressure fall. It simply maintains alternate system pressure.
    rwImDBs.png
    ~
  • AUTOMATIC RETURN-TO-NORMAL PRESSURE SWITCH, opens on ALTERNATE SYSTEM pressure fall. This will disconnect ground from both Transfer Valves and the ALTERNATE ON lamp. Both Transfer Valves goes back to spring loaded defaults (NORMAL open, ALTERNATE closed) and the ALTERNATE ON lamp goes out. The system switches to NORMAL SYSTEM hydraulics.
    qrTqoGM.png
    ~
  • NORMAL SYSTEM PRESSURE SWITCHES closes on NORMAL SYSTEM pressure fall. This will energize both Transfer Valves and the ALTERNATE ON lamp. System switches to ALTERNATE SYSTEM hydraulics. If switch to ALTERNATE SYSTEM is initiated by flipping the FLIGHT CONTROL cockpit switch, then NORMAL SYSTEM TRANSFER VALVE operates immediately which in turn sequentially causes NORMAL SYSTEM pressure fall triggering this pressure switch to close and thereby energize the ALTERNATE SYSTEM TRANSFER VALVE and the ALTERNATE TO lamp.
    fLw5H5X.png
    ~

Finally getting to the lamp (ALTERNATE TO), well almost ... First, a pedagogical generic Push-to-Test lamp design:

 

S0pk8RD.png

 

It has 3 connections (NORMAL, TEST & COM) very similar (identical I think) to the F-86F PUSH-TO-TEST lamp:

 

a64uyQe.png

Figure 10-4. Electrical and Electronic Symbol Chart (Sheet 2 of 4)" page 680 (pdf 686) "f-86f maintenance handbook”, “LAMPS”. Note the “R” in this symbol chart just indicates color (red). ALTERNATE ON lamp is marked “A” for amber. Gauging from the no of colors listed on the symbol chart but not used on the instrument panel, was F-86F initially LGBT?:suspect:.

 

I take the "TEST" connection on both the generic Push-to-Test lamp and the F-86F PUSH-TO-TEST lamp as the same pin, both serving the actual Push-to-Test functionality. Then pin 1. COMMON and pin 2. CONTROL are normally connected through the lamp (unpushed). Pin 1 and pin 3 would connect to the lamp when pushed.

This is consistent with how another F-86F push test lamp works; the RUDDER TRIM & TAKE-OFF INDICATOR lamp, figure 2-21 (page 88, pdf 94) "f-86f maintenance handbook". Here pin 3 is hard grounded and pin 1 is hard tied to 28V primary bus. Assuming pin 3 has the push test functionality, the push test would function.

 

Looking at the lamp on the schematics (fig 2-26) there's one connection going left (pin 2. CONTROL), one going right (pin 1. COMMON) and one going straight up (pin 3. TEST).

 

CvbbWWw.png

 

Pin 2

------

Pin 2 is normally grounded via the AUTOMATIC RETURN-TO-NORMAL PRESSURE SWITCH (two switches in parallel). It remains grounded as long as the ALTERNATE SYSTEM pressure is nominal (high) and disconnects from ground only when this pressure drops.

Pin 2 is also hard tied to both NORMAL SYSTEM TRANSFER VALVE and ALTERNATE SYSTEM TRANSFER VALVE solenoid coils. The AUTOMATIC RETURN-TO-NORMAL PRESSURE SWITCH grounds both Transfer Valves solenoid coils and the lamp when closed.

 

Pin 1

------

Pin 1 is hard tied to the ALTERNATE SYSTEM TRANSFER VALVE non-grounded side solenoid coil. It is also connected to NORMAL SYSTEM TRANSFER VALVE non-grounded side solenoid coil except for brief moments when the switch to ALTERNATE SYSTEM is initiated by the cockpit FLIGHT CONTROL switch. In the latter situation, the tied together pin 1 and ALTERNATE SYSTEM TRANSFER VALVE (non-ground side) are free floating until the NORMAL SYSTEM PRESSURE SWITCHES closes due to pressure drop.

 

Pin 3

-----

Pin 3 is always hard tied to 24/28V (unless a circuit breaker pops).

 

The ALTERNATE TO lamp will shine (pin 1 positive, pin 2 grounded) whenever ALTERNATE SYSTEM TRANSFER VALVE is energized because the lamp is hard tied in parallel with the Valve coil.

The ALTERNATE TO lamp will also shine (I maintain) when pushed-to-test in NORMAL hydraulic mode. This because the Push-to-Test pin 3 is hard tied to 24/28V and pin 1 is grounded as I lay out up top in summation, through the ALTERNATE SYSTEM TRANSFER VALVE operating coil and through the AUTOMATIC RETURN-TO-NORMAL PRESSURE SWITCH.

The ALTERNATE TO lamp will go dark if pushed while ALTERNATE SYSTEM is active. This because (again as layed out up top) pin 1 is 24/28V and pin 3 is also 24/28V.

 

 

Some random observations

--------------------------

Switching electrically to ALTERNATE SYSTEM is only ever possible while ALTERNATE SYSTEM pressure is nominal (high enough)) because the AUTOMATIC RETURN-TO-NORMAL PRESSURE SWITCH won't ground the Transfer Valves coils (both + the lamp) if it isn't.

 

Switching mechanically to ALTERNATE SYSTEM is always possible by pulling the ALTERNATE HYDRAULIC SYSTEM OVERRIDE SWITCH. This will mechanically pull both Transfer valves and connect Battery to ALTERNATE SYSTEM PUMP (manual "if without generator ... run down the battery in 6-7 minutes" <ouch>.

 

The ALTERNATE SYSTEM TRANSFER VALVE can only ever be energized by the closing of the NORMAL SYSTEM PRESSURE SWITCHES. Meaning a switch to the ALTERNATE system requires a pressure drop in the NORMAL system. A pressure drop in the NORMAL system can happen in least three ways:

1) NORMAL system gets damaged.

2) Engine RPM is low and vigorous stick jerking "uses up" available NORMAL system pressure.

3) The FLIGHT CONTROL switch (in cockpit) is switched from NORMAL to ALTERNATE. This closes the NORMAL SYSTEM TRANSFER VALVE and pressure drops.

 

(Cockpit) First flipping FLIGHT CONTROL to RESET is required to change from ALTERNATE to NORMAL. On RESET both Transfer Valves looses power and starts going to spring loaded defaults. RESET must remain a small amount of time to allow Transfer Valves to go to defaults and let NORMAL pressure rise and ALTERNATE pressure fall until they affect pressure switches.

 

Figure 2-27 is identical to figure 2-26 except system is shown in ALTERNATE mode.

 

Chart reading. Crossed lines with little circles are connected (otherwise, not).


Edited by -0303-

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Wow 0303, that's pretty thorough. Plus skimming through it, seems correct too - I've a background in electronic and SW engineering so am able to follow you, at least to an extent.

 

Alas, this is an old bird, so I wouldn't count on a fix being released anytime soon. But one can always hope...

The DCS Mi-8MTV2. The best aviational BBW experience you could ever dream of.

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... Try to connect lamp to electric bus and ground.

 

A shorter version of my previous post.

 

In NORMAL boost hydraulic mode. Red is battery and primary bus connected to pin 3 of push lamp. Green is grounding connected to pin 1 of push lamp. Grounding through the ALTERNATE SYSTEM TRANSFER VALVE solenoid coils and the AUTOMATIC RETURN-TO-NORMAL PRESSURE SWITCH grounds the solenoid as long as Alternate pressure is nominal.

What happen if DC current passes through a coil and why ?

 

Nothing special should happen. If we neglect the proper impedance of the wire, the theoretical impedance of the coil is proportional to the frequency : Zcoil = j.L.ω with ω = 2.π.f and L the inductance of the coil.

If the current is DC then f = 0 and consequently Zcoil = 0, the coil acts only as a wire.

https://www.researchgate.net/post/What_happen_if_DC_current_passes_through_a_coil_and_why

V9j4ncJ.png

 

Also, if in ALTERNATE hydraulic mode, lamp should go dark if pushed (see previous post).

 

~


Edited by -0303-

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I've a background in electronic and SW engineering so am able to follow you, at least to an extent.

This is not advanced electronics in any way. It's switches, it's mostly about having the patience to figure out what happens and why.

I did work for a decade and a half in electronics, years ago (I'm always vague on personal details on the internet).

 

I seem to remember coils are DC short circuits. But there was never much reason to measure coils (for me). I did look a lot for short circuits, much more to find connections from the schematics in the actual hardware, than to find actual faulty short circuits. Again, I think I vaguely remember, coils were annoying in that they registered as short circuit even if there wasn't one.

 

I have a solder iron, a multi-meter and a small breadboard laying around (I even have an oscilloscope, from the 70's, got it real cheap, but working last I checked). If I can find an old broken phone to find a coil and a diode, maybe I could show that a lamp would shine. But don't count on it.

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