Wheel well fire test

[Driver170 42]

How can i perform the wheel well fire test? i'm at loss with this one

[Spin737 102]

Have AC power and do the fire test.

[Driver170 42]

I have AC power! Where exactly is the wheel well fire test?

[downscc 1,327]

FCOM 8.20.8; the detector loop in the main wheel well is tested along with the other fire loops.

[Driver170 42]

I thought that. The reason i ask because i seen it as a seperate tests so assumed it was a switch on the fire panel, but i couldn't see it anywhere.

[Driver170 42]

Why in my FCOM you have the wheel well fire test seperate?

 

If APU power is needed:

Verify that the engine No. 1, APU and the engine No. 2 fire switches

are in.

Alert ground personnel before the following test is accomplished.

OVERHEAT DETECTOR switches – NORMAL

TEST switch – Hold to FAULT/INOP

Verify that the MASTER CAUTION lights are illuminated.

Verify that the OVHT/DET annunciator is illuminated.

Verify that the FAULT light is illuminated.

If the FAULT light fails to illuminate, the fault monitoring

system is inoperative.

 

Verify that the APU DET INOP light is illuminated.

Do not operate the APU if the APU DET INOP light fails to

illuminate.

 

TEST switch – Hold to OVHT/FIRE

Verify that the fire warning bell sounds.

Verify that the master FIRE WARN lights are illuminated.

Verify that the MASTER CAUTION lights are illuminated.

Verify that the OVHT/DET annunciator is illuminated.

Master FIRE WARN light – Push

Verify that the master FIRE WARN lights are extinguished.

Verify that the fire warning bell cancels.

Verify that the engine No. 1, APU and the engine No. 2 fire

switches stay illuminated.

Verify that the ENG 1 OVERHEAT and ENG 2 OVERHEAT

lights stay illuminated.

 

 

 

 

 

Wheel well fire warning system ................................................... Test

 

 

Test switch – Hold to OVHT/FIRE

Verify fire warning bell sounds, master FIRE WARN lights,

MASTER CAUTION lights and OVHT/DET annunciator

illuminate.

 

Fire warning BELL CUTOUT switch – Push

Verify that the master FIRE WARN lights extinguish.

Verify that the fire warning bell cancels.

Verify that the WHEEL WELL fire warning light is

illuminated

 

[mcnobody 172]

There is no seperate test switch for the WHEEL WELL FIRE DETECTOR. You just need to use the Overheat/Fire (OVHT/FIRE) TEST Switch on the AFT ELECTRONIC PANEL.
 

 

A quote from the FCOM:

Fault/Inoperative (FAULT/INOP) and
Overheat/Fire (OVHT/FIRE) TEST Switch
(spring–loaded to center)

FAULT/INOP – tests fault detection circuits for both engines and the APU.
OVHT/FIRE – tests overheat and fire detection loops on both engines and APU, and wheel well fire detector

Note: See Fire and Overheat Detection System Fault Test in Section 20.

[Driver170 42]

Yeh but if you look at the electrical power up SP its seperate?

 

 

There is no seperate test switch for the WHEEL WELL FIRE DETECTOR. You just need to use the Overheat/Fire (OVHT/FIRE) TEST Switch on the AFT ELECTRONIC PANEL.
 

 
A quote from the FCOM:

Fault/Inoperative (FAULT/INOP) and
Overheat/Fire (OVHT/FIRE) TEST Switch
(spring–loaded to center)

FAULT/INOP – tests fault detection circuits for both engines and the APU.
OVHT/FIRE – tests overheat and fire detection loops on both engines and APU, and wheel well fire detector

Note: See Fire and Overheat Detection System Fault Test in Section 20.

 

Thanks for taking your time for that detailed description

[mcnobody 172]

Yeh but if you look at the electrical power up SP its seperate?

 

 

 

Thanks for taking your time for that detailed description

 

The electrical power up doesn't mention a seperate switch at all. It states to test the wheel well fire warning system and this is done by switching the TEST switch to OVHT/FIRE and verify and check the different items.

[Driver170 42]

Not a seperate switch but a seperate test

[mcnobody 172]

Because the WHEEL WELL FIRE DETECTOR system seems to depend on AC power being available which does not have to be the case when you are just powering up the aircraft.

 

Just load the Cold & Dark cockpit state and go through the electrical power up procedure to the first TEST switch – Hold to OVHT/FIRE item. Without ground power being connected or the APU already running you only got DC powering the aircraft, the WHEEL WELL fire warning will not illuminate while perfomring the test.

 

If you go further through the procedure you'll see that the APU is started and AC power is provided. Then perfom the OVHT/FIRE test again – as mentioned in the electrical power up – and see which lights are going to illuminate as well. Magic isn't? :smile:

 

By the way the AOM I got has four additional words included in the test, the rest goes as Boeing described it:

Wheel well fire warning system (If not already tested).................................. Test

Further more just to quote Volume 2 of the FCOM (p. 393) coming with the NGX:

 

Main Wheel Well Fire Protection

 

Main wheel well fire protection consists of fire detection powered by the No. 2 AC transfer bus.

Note:The main wheel well has no fire extinguishing system. The nose wheel well does not have a fire detection system.

 

Now don't ask me why the WHEEL WELL FIRE SYSTEM DETECTOR is specifially connected to the AC system.

[Driver170 42]

Thanks i see the logic of it now. were all just learning

 

So why is the AC system connected?