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Jet Engine "Extinguisher Relief Indicator"?  
User currently offlineMr Spaceman From Canada, joined Mar 2001, 2787 posts, RR: 9
Posted (10 years 11 months 2 weeks 2 days ago) and read 3841 times:

Hi guys.

On the side of the engine cowling of the Avroliner 146-RJ85 in the photo below you can see a small square placard located below a small round hole (view it large!) that reads ......

EXTINGUISHER
RELIEF
INDICATOR


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Click here for bigger photo!

Photo © Dion Fuchs



I suspect this feature/hole has something to do with the engine's fire bottles.

My questions are....... What is being indicated?

Is it that the fire extinguisher is fully charged?
Is it that the extinguisher has been used and thus needs servicing?
Is this object a pre flight "walk around" check for the pilots or strickly used by maintenance personnel?

What does this round object/hole do? Does it change colour? Does an object stick out of it when it's indicating?

Finally, do other jet airliner's engine's have these Extinguisher Indicators on the outside of their cowlings?

Thanks,

Chris  Smile




"Just a minute while I re-invent myself"
15 replies: All unread, jump to last
 
User currently offlineAvt007 From Canada, joined Jul 2000, 2132 posts, RR: 5
Reply 1, posted (10 years 11 months 2 weeks 2 days ago) and read 3802 times:

Pretty much every aircraft will have these, though the location varies. Some are on the fuselage, some on the cowling. There are nromally two for each fire bottle. This picute only shows one, but the idea is that when the bottle is discharged, some of the pressure is sent down a second line to the indicator, which is a coloured metal disc. At the end of the line is a springloaded piston wi tha pin on the end of it. The pressure moves the piston, and the pin pushes out the disc, which is just clipped in place. The disc falss out, indicating a discharge. It is a quick thing to glance at and see if the bottle has been blown. Whether the pilots look at it is a matter for the operators SOP. When there are two indicators, the red one means the bottle blew because the internal pressure rose too high, and was vented overboard before the bottle exploded. The yellow one is for an intentional discharge by the crew.

User currently offlineMr Spaceman From Canada, joined Mar 2001, 2787 posts, RR: 9
Reply 2, posted (10 years 11 months 2 weeks 2 days ago) and read 3803 times:

Hello Avt007.

Wow, that was a quick reply and very much appreciated.  Big thumbs up

Thank You, sir for the detailed info on what that object is for and how it works. It's pretty neat to me to learn about the smaller less obvious gadgets that can be found on an airliner's body and engines.

Take Care,

Chris  Smile



"Just a minute while I re-invent myself"
User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3702 posts, RR: 34
Reply 3, posted (10 years 11 months 2 weeks 1 day 23 hours ago) and read 3788 times:
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The yellow one is for an intentional discharge by the crew.

I've never heard of that before. I would have thought the Tech Log entry after an intentional discharge would have been enough.


User currently offlineAvt007 From Canada, joined Jul 2000, 2132 posts, RR: 5
Reply 4, posted (10 years 11 months 2 weeks 1 day 22 hours ago) and read 3750 times:

Perhaps "intentional" is a bad word. The yellow disc is only blown out if the bottle is discharged by the squib, through the cockpit switch. More than one bottle has been blown unintentionally.  Smile
Spaceman- you're welcome! I enjoy showing off my knowledge as much as the next guy!  Big thumbs up


User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3702 posts, RR: 34
Reply 5, posted (10 years 11 months 2 weeks 1 day 14 hours ago) and read 3707 times:
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What a/c have yellow disc's?

If a squib blew through a faulty c/pit switch a squib test would ident the problem and the bottle LP Lt's in the cockpit would be illuminated in my experience.


User currently offlineMusang From United Kingdom, joined Apr 2001, 872 posts, RR: 7
Reply 6, posted (10 years 11 months 2 weeks 12 hours ago) and read 3639 times:

On the RJ and, I believe, the 146 because in many ways they're identical, the green disc blows out if there is a thermal discharge of the fire bottle, i.e. its an over-pressure relief system to vent the extinguisher if for some reason it gets too hot (and therefore its internal pressure gets dangerous).

There are two extinguisher bottles per engine, located in the front of the cowling. If the green disc is blown out, the inside of the "bowl" shaped end of the pipe is revealed, which is red. One each side of each pod. On the preflight, a simple task to check each of the eight green discs.

Similarly, the aircraft has an oxygen bottle discharge disc on the lower right side just forward of the baggage hold, with a white disc. If that blows, according to the manual, streamers are deployed, to attract attention. Never seen it, not even a picture, so don't know how long the streamers are or what colour.

Regards - Musang


User currently offlineFDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 34
Reply 7, posted (10 years 11 months 2 weeks 9 hours ago) and read 3630 times:

The 727 has the yellow disc just below #3 engine pylon. Works as AVT described.


You're only as good as your last departure.
User currently offlineDC-10Tech From United States of America, joined Jun 2001, 298 posts, RR: 2
Reply 8, posted (10 years 11 months 2 weeks 9 hours ago) and read 3628 times:

Real airplanes have a light in the cockpit that tells you the bottle is empty.  Wink/being sarcastic


Forums.AMTCentral.com
User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3702 posts, RR: 34
Reply 9, posted (10 years 11 months 2 weeks 8 hours ago) and read 3628 times:
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The 727 has the yellow disc

Funny you should say that because I was thinking about it after I posed the question and thought I could remember yellow disc's on 707 # 2 & 3 sailboat fairings. As it has been 22 years since I last worked on one I couldn't remember. So if the 72 has them the 70 must have had them.

Real airplanes have a light in the cockpit that tells you the bottle is empty. - Couldn't agree more  Smile


User currently offlineCdfmxtech From United States of America, joined Jul 2000, 1341 posts, RR: 26
Reply 10, posted (10 years 11 months 2 weeks 8 hours ago) and read 3621 times:

Classic 737 APUs have 2 disks on the right side of the tail area to indicate either a normal discharge (yellow), or a thermal discharge (red). Either way, there is an APU Bottle discharge light in the flightdeck. Missing indicators indicate the above mentioned conditions.

User currently offlineAvt007 From Canada, joined Jul 2000, 2132 posts, RR: 5
Reply 11, posted (10 years 11 months 2 weeks 1 hour ago) and read 3603 times:

Lights are good too, and most planes I`ve worked have them, but don`t think thats foolproof too. Always have a backup! Discs don`t need power, they can`t burn out like lamps, they are basic and fairly foolproof, yet I have seen the odd disc fall out for no reason, except maybe they weren`t installed properly.

User currently offlineFDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 34
Reply 12, posted (10 years 11 months 1 week 6 days 23 hours ago) and read 3584 times:

>>>Real airplanes have a light in the cockpit that tells you the bottle is empty.<<<

The 727 has those as well.




You're only as good as your last departure.
User currently offlineMD11Engineer From Germany, joined Oct 2003, 14130 posts, RR: 62
Reply 13, posted (10 years 11 months 1 week 6 days 17 hours ago) and read 3577 times:

The 747 Classic with PW Jt9D-7Q as well, two on each pylon, one for each bottle... and one for the APU bottle on the tail

Jan


User currently offlineMusang From United Kingdom, joined Apr 2001, 872 posts, RR: 7
Reply 14, posted (10 years 11 months 1 week 6 days 8 hours ago) and read 3561 times:

Just so it doesn't feel left out - the 146/RJ series have lights for all 9 bottles in the f/deck!

Regards - Musang


User currently offlineUAL Bagsmasher From United States of America, joined Sep 1999, 2148 posts, RR: 10
Reply 15, posted (10 years 11 months 1 week 6 days 7 hours ago) and read 3560 times:

LOL I just had a practical on this yesterday. I had to inspect the fire supression system on our T-39A. Bottle pressures, lines, and disks. Disks were missing and the bottles were low. Gee go figure...at a school and all.... Big grin

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