Firewall forward fire protection.
Firewall forward fire protection.
(OP)
Actually posting a dayjob question for once!
G.A. Cabin air control valve. There is a cable operated stainless steel shut off valve at the firewall. However there is also a proportioning valve that's driven by a COTS electric actuator. We have certified the actuator to Part25 Appendix F (b)(4) Vertical Test "12 second vertical burn test" as usually these are put in the cabin.
I inherited the project and now, I've been asked separate the shut off and proportioning valve. Shut off valve stays stainless. proportioning valve became composite... they got picky about composites so I asked for what burn spec they are designing to and was told AC 20-135 "fire resistant". The duct no problem... but the COTS actuator is going to melt/fail/ possibly catch on fire. I've not subjected it to 2000°F for 5 minutes!
Thoughts?
G.A. Cabin air control valve. There is a cable operated stainless steel shut off valve at the firewall. However there is also a proportioning valve that's driven by a COTS electric actuator. We have certified the actuator to Part25 Appendix F (b)(4) Vertical Test "12 second vertical burn test" as usually these are put in the cabin.
I inherited the project and now, I've been asked separate the shut off and proportioning valve. Shut off valve stays stainless. proportioning valve became composite... they got picky about composites so I asked for what burn spec they are designing to and was told AC 20-135 "fire resistant". The duct no problem... but the COTS actuator is going to melt/fail/ possibly catch on fire. I've not subjected it to 2000°F for 5 minutes!
Thoughts?
RE: Firewall forward fire protection.
The shut-off valve maintains the integrity of the firewall so no problem there unless the proportioning valve penetrates the firewall or its failure would also cause the failure of the shut-off valve.
RE: Firewall forward fire protection.
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RE: Firewall forward fire protection.
RE: Firewall forward fire protection.
Quite-often fire/heat/tear-resistant sleeves or jackets, or fire-resistant enclosures are usually required for fluid hoses, wire harnesses, certain mechanical/electrical components and fuel cutoff valves in engine bays.
Any way a damaged valve [case/attaching duct etc] could allow force-fed flames into the cabin-air duct work? Air-flow surrounding engines has a pesky way of pressurizing heat/flames thru the tiniest holes into undesirable locations. I could tell You some hair-raising fire/heat penetration 'war-stories'... Naw.
BE EXCEPTIONALLY careful about any adjacent flammables or electrical power wires in fire-rated compartments.
Is there any porous insulation [etc] that could trap/retain leaking flammables... oil, grease, fuel, etc... nearby?
Also is there any urgent need for high-electrical-energy bonding/grounding of the component to the airframe??
Just saying... probably over-thinking this... it's late.
Regards, Wil Taylor
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