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Dave Saylor
Joined: 11 Jan 2015
Posts: 209
Location: GILROY, CA
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 Posted: Wed Oct 07, 2020 7:17 pm Post subject: Breaker then pump failure |
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I just had the Tyco switch/breaker for my boost pump fail. It made a bad smell, then became intermittent, then failed completely in the span of a few minutes. I replaced it with the same make and model.
2.5 flight hours later my boost pump failed. The new breaker never tripped. The pump just stopped running. The pump circuit has no resistance and I get full bus voltage at the pump, even with the pump still connected. So it's open inside. The new switch is working fine.
The pump is from Airflow Performance. They're common in RVs. The pump and the switch had almost 2000 airframe hours since installed. I use it for take-off and landing, so the powered time is a fraction of the total time.
The airplane had been sitting for almost a year, then flown about 15 hours in the last two weeks.
Does anyone have an understanding of any relationship between these two failures? They seem too similar to be completely unrelated. My guess is that a faulty pump somehow overloaded a faulty breaker, then failed completely. I couldn't say that I noticed any particular fuel pressure issues before the failure. Everything was in the green.
Thoughts?
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nuckolls.bob(at)aeroelect
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| Posted: Thu Oct 08, 2020 8:34 am Post subject: Breaker then pump failure |
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At 10:14 PM 10/7/2020, you wrote:
I just had the Tyco switch/breaker for my boost pump fail. It made a bad smell, then became intermittent, then failed completely in the span of a few minutes. I replaced it with the same make and model.
Do you still have the carcass? I'd like to have
it . . .
2.5 flight hours later my boost pump failed. The new breaker never tripped. The pump just stopped running. The pump circuit has no resistance and I get full bus voltage at the pump, even with the pump still connected. So it's open inside. The new switch is working fine.
Agreed
The pump is from Airflow Performance. They're common in RVs. The pump and the switch had almost 2000 airframe hours since installed. I use it for take-off and landing, so the powered time is a fraction of the total time.
I think that pump has a PM motor with brushes.
It's not uncommon for such devices to suffer
as much degradation from idle time as from
service life. In any case, I'm betting that
the pathway through the armature is open for
reasons we do not yet know. Does the pump
have a 'cure' value? If not, I'd be pleased
to do a autopsy on it too.
The airplane had been sitting for almost a year, then flown about 15 hours in the last two weeks.
Does anyone have an understanding of any relationship between these two failures? They seem too similar to be completely unrelated. My guess is that a faulty pump somehow overloaded a faulty breaker, then failed completely. I couldn't say that I noticed any particular fuel pressure issues before the failure. Everything was in the green.
Thoughts?
I suspect they are not related. In theory, you
can't damage a breaker by 'overloading' it . . . after
all, its core mission in life is to protect from
the consequences of such conditions including self
destruction. Getting a look at the carcasses might
offer more clues.
Bob . . .
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ceengland7(at)gmail.com
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| Posted: Thu Oct 08, 2020 9:05 am Post subject: Breaker then pump failure |
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On Thu, Oct 8, 2020 at 11:42 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 10:14 PM 10/7/2020, you wrote:
snipped .
2.5 flight hours later my boost pump failed. The new breaker never tripped. The pump just stopped running. The pump circuit has no resistance and I get full bus voltage at the pump, even with the pump still connected. So it's open inside. The new switch is working fine.
 Agreed
Â
The pump is from Airflow Performance. They're common in RVs. The pump and the switch had almost 2000 airframe hours since installed. I use it for take-off and landing, so the powered time is a fraction of the total time.
 I think that pump has a PM motor with brushes.
 It's not uncommon for such devices to suffer
 as much degradation from idle time as from
 service life. In any case, I'm betting that
 the pathway through the armature is open for
 reasons we do not yet know. Does the pump
 have a 'cure' value? If not, I'd be pleased
 to do a autopsy on it too.
The airplane had been sitting for almost a year, then flown about 15 hours in the last two weeks.
Does anyone have an understanding of any relationship between these two failures? They seem too similar to be completely unrelated. My guess is that a faulty pump somehow overloaded a faulty breaker, then failed completely. I couldn't say that I noticed any particular fuel pressure issues before the failure. Everything was in the green.
Thoughts?
 I suspect they are not related. In theory, you
 can't damage a breaker by 'overloading' it . . . after
 all, its core mission in life is to protect from
 the consequences of such conditions including self
 destruction. Getting a look at the carcasses might
 offer more clues.
 Bob . . .
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The core pump in the AFP pumps I'm familiar with are Airtex brand in-line fuel injection pumps, available online for between $60 & $100. Like this?
https://www.amazon.com/Airtex-E2000-Electric-Fuel-Pump/dp/B000C1KHJG/ref=sr_1_7?dchild=1&keywords=airtex+fep2000+fuel+pump&qid=1602176199&sr=8-7
Either E2000 or FEP2000. Note that the hose barb shown on one end screws off, allowing various other adapters.
If the OP wishes, I can measure my FEP2000Â to verify dimensions.Â
Charlie
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nuckolls.bob(at)aeroelect
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| Posted: Thu Oct 08, 2020 11:13 am Post subject: Breaker then pump failure |
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Interesting. The specs speak to commutators and
brushes. I also deduce that this style of pump
is used on a lot of medium pressure EFI systems.
It will be interesting to see if we can open
Dave's dead one for a closer looksee.
Bob . . .
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Thu Oct 08, 2020 3:58 pm Post subject: Breaker then pump failure |
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I believe Airflow Performance with do a rebuild at reasonable price.
Might not get the diagnosis desired, but could be cheaper than alternatives.
On 10/8/2020 12:08 PM, Robert L. Nuckolls, III wrote:
| Quote: | >
> The core pump in the AFP pumps I'm familiar with are Airtex brand
> in-line fuel injection pumps, available online for between $60 & $100.
> Like this?
> https://www.amazon.com/Airtex-E2000-Electric-Fuel-Pump/dp/B000C1KHJG/ref=sr_1_7?dchild=1&keywords=airtex+fep2000+fuel+pump&qid=1602176199&sr=8-7
>
> Either E2000 or FEP2000. Note that the hose barb shown on one end
> screws off, allowing various other adapters.
> If the OP wishes, I can measure my FEP2000Â to verify dimensions.Â
>
> Charlie
Interesting. The specs speak to commutators and
brushes. I also deduce that this style of pump
is used on a lot of medium pressure EFI systems.
It will be interesting to see if we can open
Dave's dead one for a closer looksee.
Bob . . .
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Dave Saylor
Joined: 11 Jan 2015
Posts: 209
Location: GILROY, CA
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| Posted: Thu Oct 08, 2020 9:18 pm Post subject: Breaker then pump failure |
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Charlie wrote:
Â
Between Amazon and the Airtex web site, my pump seems most like an E8445. There are a lot of models and I haven't ID'd it exactly. The E2000 looks the same but it puts out almost three times the pressure that I see.
I sent my pump assy to AFP where they replaced the pump for a little more than the Amazon price. They did a great job, shipping back the repaired assembly within hours of receiving it.
Bob, if I get the old pump back, I'll send it to you along with the breaker.
BTW, I just became aware of an AD from 2008 to replace this type of CB switch in Beechcraft products.
--Dave
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Dave Saylor
Joined: 11 Jan 2015
Posts: 209
Location: GILROY, CA
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| Posted: Thu Oct 08, 2020 9:53 pm Post subject: Breaker then pump failure |
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Bob wrote:
| Quote: | Â Do you still have the carcass? I'd like to have
 it . . .
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Here's a picture for now. I broke in before I sent my initial message. Charred remains to follow.
I'm almost certain that the braid broke when I opened it.
The little barbequed U spring is missing most of its legs. I wonder if one broke off and shorted something to start the failure.Â
The switch had lost it's "snap" after it quit.
Here's a picture from a Beech website. These are serviceable and very similar to what I have.
[img]cid:ii_kg1tn0im1[/img]
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finn.usa(at)gmail.com
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| Posted: Fri Oct 09, 2020 6:22 am Post subject: Breaker then pump failure |
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NO. The braid is the weak point.
Where it's spot welded to the contact it's hardened. As the switch is turned on/off the braid flexes. Same as what happens when you have a soldered flexible wire that is not supported at a point where the wire is still flexible (after the solder penetration).
It's a glaring design failure. Easily fixed by two molded pins in the plastic housing that would provide support where braid is again flexible. Why they haven't done that after the extensive failure history is beyond me.
Do not use these switch/breakers for flight-critical items!
Finn
[img]cid:part1.DBFBFD4E.1966774E(at)gmail.com[/img] On 10/9/2020 1:50 AM, David Saylor wrote:
| Quote: |
Bob wrote:
| Quote: | Â Do you still have the carcass? I'd like to have
 it . . .
|
Here's a picture for now. I broke in before I sent my initial message. Charred remains to follow.
I'm almost certain that the braid broke when I opened it.
The little barbequed U spring is missing most of its legs. I wonder if one broke off and shorted something to start the failure.Â
The switch had lost it's "snap" after it quit.
Here's a picture from a Beech website. These are serviceable and very similar to what I have.
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Ceengland
Joined: 11 Oct 2020
Posts: 391
Location: MS
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| Posted: Mon Oct 12, 2020 5:44 am Post subject: Breaker then pump failure |
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On Fri, Oct 9, 2020 at 12:24 AM David Saylor <saylor.dave(at)gmail.com (saylor.dave(at)gmail.com)> wrote:
| Quote: | Charlie wrote:
Â
Between Amazon and the Airtex web site, my pump seems most like an E8445. There are a lot of models and I haven't ID'd it exactly. The E2000 looks the same but it puts out almost three times the pressure that I see.
I sent my pump assy to AFP where they replaced the pump for a little more than the Amazon price. They did a great job, shipping back the repaired assembly within hours of receiving it.
Bob, if I get the old pump back, I'll send it to you along with the breaker.
BTW, I just became aware of an AD from 2008 to replace this type of CB switch in Beechcraft products.
--Dave
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Congrats on the inexpensive repair! The reason I'd bet on the E2000 is that the E8445 appears to have a fixed hose barb output, while the E2000 has a threaded fitting on the output, allowing choice of fittings. Note that both pumps are capable of much higher pressure (and volume) than Bendix injection (or even automotive electronic injection) uses. Both types require a mechanical 'bypass' style pressure regulator to set pressure, and excess fuel is vented by the regulator. In the older cars where these pumps were used, the bypassed fuel returned to the fuel tank. With the AFP pump assembly, that extra block of metal in the assembly is the regulator and routes the bypassed fuel back to the pump inlet. In later models, the same device functions as a check valve, allowing the engine's mechanical pump to 'suck' fuel around the electric pump itself. Earlier models had a separate check valve, IIRC.
Charlie
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Mon Oct 12, 2020 6:01 am Post subject: Breaker then pump failure |
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That AD is rather controversial, in that the exact same breaker is used
in many other plane models and brands, but the AD was only issued
against specific Beech models.
Kelly
On 10/12/2020 6:37 AM, Charlie England wrote:
| Quote: | BTW, I just became aware of an AD from 2008 to replace this type of
CB switch in Beechcraft products.
--Dave
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Dave Saylor
Joined: 11 Jan 2015
Posts: 209
Location: GILROY, CA
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| Posted: Mon Oct 12, 2020 7:31 am Post subject: Breaker then pump failure |
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Charlie,
The one that came back looked identical. Same threaded inlet, same banjo outlet, same terminals. It's marked "Delphi FD0011". Delphi has a store on Amazon, and the description is for a solenoid pump.
The new one sounds much different. I suppose it's a healthier sound now but it seems much higher pitch.
AFP didn't send the old one back.
--Dave
Â
| Quote: |
Congrats on the inexpensive repair! The reason I'd bet on the E2000 is that the E8445 appears to have a fixed hose barb output, while the E2000 has a threaded fitting on the output, allowing choice of fittings. Note that both pumps are capable of much higher pressure (and volume) than Bendix injection (or even automotive electronic injection) uses. Both types require a mechanical 'bypass' style pressure regulator to set pressure, and excess fuel is vented by the regulator. In the older cars where these pumps were used, the bypassed fuel returned to the fuel tank. With the AFP pump assembly, that extra block of metal in the assembly is the regulator and routes the bypassed fuel back to the pump inlet. In later models, the same device functions as a check valve, allowing the engine's mechanical pump to 'suck' fuel around the electric pump itself. Earlier models had a separate check valve, IIRC.
Charlie
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Dave Saylor
Joined: 11 Jan 2015
Posts: 209
Location: GILROY, CA
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| Posted: Mon Oct 12, 2020 7:32 am Post subject: Breaker then pump failure |
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Very interesting Finn. That makes a lot of sense.
On Fri, Oct 9, 2020 at 7:31 AM Finn Lassen <finn.usa(at)gmail.com (finn.usa(at)gmail.com)> wrote:
| Quote: |
NO. The braid is the weak point.
Where it's spot welded to the contact it's hardened. As the switch is turned on/off the braid flexes. Same as what happens when you have a soldered flexible wire that is not supported at a point where the wire is still flexible (after the solder penetration).
|
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nuckolls.bob(at)aeroelect
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| Posted: Mon Oct 12, 2020 8:04 am Post subject: Breaker then pump failure |
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At 08:58 AM 10/12/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: Kelly McMullen <kellym(at)aviating.com>
That AD is rather controversial, in that the exact same breaker is used in many other plane models and brands, but the AD was only issued against specific Beech models.
Kelly |
I was on the team that worked that issue at Beech.
The failure mode that started the investigation
involved switch-breakers subject to the highest of
ship's loads, i.e. electric prop de-ice. I know that
same s/b was used on some Cessna models . . . but
perhaps only on lightly loaded circuits.
Root cause is a mechanical issue. The fine strand
jumper wire starts to loose strands due to operational
flexing of the jumper.
In the incident switches, loss of that jumper caused
system current to flow through the spring. For the
smaller switches, 5-10A, there is no immediate
indication of failure. For the higher current
applications, the spring heats up causing
smoke from the burning of the switch's housing.
I read that the smoke rather jetted from around
the switch's actuator handle.
Here's my library of photos and illustrations
generated to support my task at Beech along
with documents speaking to field responses.
https://tinyurl.com/y48y93rk
I worked analysis of the carcasses while others
researched affected aircraft . . . which was
a whole lot! There was a potential for thousands
of aircraft and tens of thousands of switches to be
at risk.
Cessna had a similar situation as cited in documents
offered above.
This was a tough one. Existence of the insulator
did not stop mechanical failure of the braid . . .
it only prevents smoke generation by the heavily
loaded switches. With the insulator in place,
the switch simply opens up.
Replacing all the at-risk switches in all fielded
aircraft was a really BIG deal. The Bonanza Society
and AOPA did a survey of affected aircraft owners
and came to the conclusion that the failures
were rare, occurrences of spring failure and
smoke were rarer still. They opined that these
events were very low risk and that a more relaxed
approach to dealing with the condition was
warranted. The FAA agreed.
Bob . . .
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Ceengland
Joined: 11 Oct 2020
Posts: 391
Location: MS
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| Posted: Mon Oct 12, 2020 8:26 am Post subject: Breaker then pump failure |
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The 1st hit I got on Amazon shows what appears to be a clone of the E2000. (Or the E2000 is a clone of the Delphi; who knows?   ) The Amazon ad says 'solenoid style'. Not sure what they mean by that, other than it's a cylindrical container like the activator solenoid on a starter motor. The pump is an electric motor, driving either a gerotor or roller-vane pump, all inside that housing. The sound is a whir or whine, right? Not a clicking sound. The low pressure Facet 'cube pumps' used as carb boost pumps make a clicking/buzzing/rattling sound; they are effectively 'solenoid' pumps.
Just to be sure you know...Try your best to be sure that the pump gets a prime (pumps fuel) quickly when you 1st run the pump, even if you have to open the output side so it pumps into an open container. Most pumps like these will self prime, but they will only survive for a few minutes without fuel flowing through them. Configured like the AFP 'system' with the regulator bypass back to the inlet, they sometimes *won't* self-prime because they pump air in a loop around the pump instead of sucking fuel. That can kill the pump in a few minutes.
Charlie
On Mon, Oct 12, 2020 at 10:41 AM David Saylor <saylor.dave(at)gmail.com (saylor.dave(at)gmail.com)> wrote:
| Quote: | Charlie,
The one that came back looked identical. Same threaded inlet, same banjo outlet, same terminals. It's marked "Delphi FD0011". Delphi has a store on Amazon, and the description is for a solenoid pump.
The new one sounds much different. I suppose it's a healthier sound now but it seems much higher pitch.
AFP didn't send the old one back.
--Dave
Â
| Quote: |
Congrats on the inexpensive repair! The reason I'd bet on the E2000 is that the E8445 appears to have a fixed hose barb output, while the E2000 has a threaded fitting on the output, allowing choice of fittings. Note that both pumps are capable of much higher pressure (and volume) than Bendix injection (or even automotive electronic injection) uses. Both types require a mechanical 'bypass' style pressure regulator to set pressure, and excess fuel is vented by the regulator. In the older cars where these pumps were used, the bypassed fuel returned to the fuel tank. With the AFP pump assembly, that extra block of metal in the assembly is the regulator and routes the bypassed fuel back to the pump inlet. In later models, the same device functions as a check valve, allowing the engine's mechanical pump to 'suck' fuel around the electric pump itself. Earlier models had a separate check valve, IIRC.
Charlie
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