Mr Spaceman
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What's This Bizjet Part Behind The Skin For?

Fri Jun 10, 2005 4:24 am

Hi guys.

In the Cessna Citation II bizjet photo below, you can see a small silver tank/bottle that's attached to the bulkhead under the cockpit windscreen on the jet's right side ........ what is it for?

I believe "aviation oxygen" bottles are always painted green (although I could be wrong Big grin ), so I was wondering ...... is it a fire bottle for the avionics bay in the nose?


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Photo © Jacques Lienard



PS, note the 3 tennis balls being used to cover the pitot tubes.  Silly

Chris  Smile
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SlamClick
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RE: What's This Bizjet Part Behind The Skin For?

Fri Jun 10, 2005 6:09 am

You are correct; painted green and labeled "aviator breathing oxygen."

Don't know anything about the Citation but that looks like maybe the tank for some consumbable fluid, like perhaps rain repellant? Too big to be an accumulator, fire bottles are usually round.
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citationjet
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RE: What's This Bizjet Part Behind The Skin For?

Fri Jun 10, 2005 6:24 am

The silver container on the left (most outboard) is the alcohol for the windshield anti-ice - which is a backup system. The primary windshield anti-ice system is bleed air. The alcohol provides about 10 minutes of operation to the left windshield only (pilot's window).

The silver cylinder to the right (more inboard and cylindrical) is the pneumatic bottle for emergency blow down of the gear and also pneumatic brakes - also a secondary backup system.

.

[Edited 2005-06-09 23:28:14]
Boeing Flown: 701,702,703;717;720;721,722;731,732,733,734,735,737,738,739;741,742,743,744,747SP;752,753;762,763;772,773.
 
AsstChiefMark
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RE: What's This Bizjet Part Behind The Skin For?

Fri Jun 10, 2005 7:10 am

That's the glans Cessna. It's the nerve center.

Mark
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DeltaGuy
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RE: What's This Bizjet Part Behind The Skin For?

Fri Jun 10, 2005 7:13 am

Maybe a tear duct?  Wink

DeltaGuy
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HAWK21M
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RE: What's This Bizjet Part Behind The Skin For?

Fri Jun 10, 2005 4:21 pm

Quoting Mr Spaceman (Thread starter):
note the 3 tennis balls being used to cover the pitot tubes.

Why not use Pitot covers.

Quoting CitationJet (Reply 2):
The silver cylinder to the right (more inboard and cylindrical) is the pneumatic bottle for emergency blow down of the gear and also pneumatic brakes - also a secondary backup system.

Nitrogen Cylinder What capacity/pressure.
regds
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jeb94
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RE: What's This Bizjet Part Behind The Skin For?

Fri Jun 10, 2005 5:08 pm

Tennis balls are cheaper and just as effective at covering the pitot tubes. Especially small ones like those. The tubes also low to the ground so the tennis balls are nice and soft when a person bumps into them.
 
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HAWK21M
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RE: What's This Bizjet Part Behind The Skin For?

Fri Jun 10, 2005 6:52 pm

Quoting Jeb94 (Reply 6):
The tubes also low to the ground so the tennis balls are nice and soft when a person bumps into them.

That reason could be the one.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
citationjet
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RE: What's This Bizjet Part Behind The Skin For?

Fri Jun 10, 2005 10:53 pm

Quoting HAWK21M (Reply 5):
Nitrogen Cylinder What capacity/pressure

Maint Manual says pressure must be maintained at 1,800 to 2,000 psi. Bottle volume is 100 cu in. Bottle is about 12 in long and 3.5 in diameter, about the size of a thermos bottle.

[Edited 2005-06-10 16:07:27]
Boeing Flown: 701,702,703;717;720;721,722;731,732,733,734,735,737,738,739;741,742,743,744,747SP;752,753;762,763;772,773.
 
Mr Spaceman
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RE: What's This Bizjet Part Behind The Skin For?

Sat Jun 11, 2005 12:09 am

Hi guys.

Quoting SlamClick (Reply 1):
You are correct; painted green and labeled "aviator breathing oxygen."

>> SlamClick, Thanks for letting me know for sure that "aviator breathing oxygen" bottles are infact painted green. I believe I've seen a few photos of the round fire bottles you mentioned (but couldn't find a photo  Sad ). I think they use the chemical Halon to suppress a fire.

>> CitationJet, Thank You, for your detailed info about the rectangular & cylindical silver tanks against that bulkhead. When you ask about a Cessna Citation bizjet, and a member responds who has the username "CitationJet" who's from Wichita, KS (Cessna's main home), you know you're gonna get excellent info!  bigthumbsup 

>> AsstChiefMark & DeltaGuy, Ha Haaa, that's funny!  Smile

>> HAWK21M, you asked .....

Quoting HAWK21M (Reply 5):
Why not use Pitot covers.

I was wondering the same thing. Then I thought that maybe the red flag that hangs down from them that says on it "Remove Before Flight" might get in a mechanics way ..... just a thought.

>> Jeb94, you mentioned .........

Quoting Jeb94 (Reply 6):
Tennis balls are cheaper and just as effective at covering the pitot tubes.

Regarding the cost, IMHO, there's no way that CitationJet isn't carrying proper pitot covers (and static port covers & an attitude indicator cover), somewhere inside a storage compartment (these items were kept inside a compartment in the steps of the airstair door on many Falcon 20 bizjets I used to refuel, etc).

I see you're an Aircraft Maintenance Technician, so you probably know what it's like to back into a proper pitot cover .... made of rubber or not, they're rather "pointy" aren't they!!!  mad 

I have one last question ......

The black box in the nose that the weather radar appears to be wired to has two black cylindrical objects sticking up from the top of it ....... what are these two objects for?

Chris  Smile
"Just a minute while I re-invent myself"
 
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HAWK21M
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RE: What's This Bizjet Part Behind The Skin For?

Sat Jun 11, 2005 12:46 am

Quoting Mr Spaceman (Reply 9):
The black box in the nose that the weather radar appears to be wired to has two black cylindrical objects sticking up from the top of it ....... what are these two objects for?

Could they be Gyro assys.Just my guess.  Smile
regds
MEL
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Mr Spaceman
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RE: What's This Bizjet Part Behind The Skin For?

Sat Jun 11, 2005 12:59 am

Hello HAWK21M.

Once again we're on the same wave-length. I first thought of gyros too, but, because that whole black unit appears to me to be hooked up to the radar, I though .... what would weather radar need 2 gyros for?

Hopefully someone will let us know what they are. Big grin

Chris  Smile
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citationjet
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RE: What's This Bizjet Part Behind The Skin For?

Sat Jun 11, 2005 1:34 am

Quoting Mr Spaceman (Reply 9):
When you ask about a Cessna Citation bizjet, and a member responds who has the username "CitationJet" who's from Wichita, KS (Cessna's main home), you know you're gonna get excellent info!

Thanks. It also helps when you have the flight manuals outside your office, engineering flight test pilots located down the hall, and a hanger next door that has the following prototype aircraft: Citation X (750), Citation Sovereign (680), Citation XLS (560XL), Citation CJ3 (525B), Citation Encore (560), Citation Bravo (550), Caravan 208, and the Citation Mustang (510) prototype (the only Mustang that has flown so far).
Boeing Flown: 701,702,703;717;720;721,722;731,732,733,734,735,737,738,739;741,742,743,744,747SP;752,753;762,763;772,773.
 
jeb94
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RE: What's This Bizjet Part Behind The Skin For?

Sat Jun 11, 2005 6:42 am

Hmm...does the Citation II use conventional gyros or does it have an IRS? (Inertial Reference System)
 
AvionicMech
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RE: What's This Bizjet Part Behind The Skin For?

Sat Jun 11, 2005 9:48 am

If the Citation II uses conventional gyros for the flight instruments then the weather radar transceiver would need its own gyro. The system on most commercial aircraft is linked into the IRS databus to get this data but if the Citation II doesn't have an IRS system then I guess it must have its own gyro in the transceiver, which would explain the cylindrical objects on top of the box.
 
pilotpip
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RE: What's This Bizjet Part Behind The Skin For?

Sat Jun 11, 2005 10:05 pm

CitationJet,

Have they gotten the problems with the Sovereign's nose gear resolved? I was talking to a couple CitationShares pilots a couple days ago and they said this is causing considerable backup in deliveries. The only one I've seen at STL diverted here with a broken windshield. Citations are my favorite jets, I'd like seen a new flavor at STL once in a while.
DMI
 
Mr Spaceman
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RE: What's This Bizjet Part Behind The Skin For?

Mon Jun 13, 2005 12:19 am

Hi guys.

>> CitationJet, regarding the Citation Mustang..........

Quoting CitationJet (Reply 12):
and the Citation Mustang (510) prototype (the only Mustang that has flown so far).

There's a neat article about the Citation Mustang in the May, 2005 issue of Flying magazine incase you didn't know. The 2 page article isn't about the actual aircraft itself, but rather, the "Flying Iron Bird" simulator that the engineers were using to test it's systems before the first real flight.

It's the first time I've learned about "Iron Birds" being used during the development of a new aircraft prototype.

Here's some info from the article .......

"The flying iron bird is actually a very accurate simulation of an airplane that doesn't yet exist."

"The cockpit of the flying iron bird is an open platform with aircraft seats, but the instrument panel in front of the pilots is the exact size and shape of the Mustang."

"Mounted several feet ahead of the cockpit is a large, and very wide visual display that creates powerful illusions of attitude change, even though the cockpit is stationary."

"In the panel are the three big displays of the Garmin G1000 avionics system, which are exactly like those used in the real airplane."

"The red control wheel on the left side of the Cessna Mustang "iron bird" contains sensors that measure forces pilots apply to the wheel."

The article explains how flight loads of each control surface over the range of airspeeds and configurations of the actual aircraft are tested using programmed electric load torque motors & computer fluid design programs, etc, etc, etc....

If I type out anymore info, nobody will need to read the article!!!  Silly

>> CitationJet, I'm just curious ...... were you involved with the Mustang Iron Bird? If not, did you get to see it?

>> Jeb94, AvionicMech & Pilotpip, hopefully CitationJet (or anyone), will let us know the answers to our questions. Big grin

Also guys, I don't understand why a weather radar transceiver that isn't linked to an IRS needs a mechanism that performs "Ridgidity In Space" (a gyro). Can the reason be briefly explained, or is it a way more complicated system than a gyro in a Artificial Horizon, HSI, or Turn/BanK Indicator?

Chris  Smile
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OzLAME
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RE: What's This Bizjet Part Behind The Skin For?

Tue Jun 14, 2005 9:40 am

Quoting AvionicMech (Reply 14):
If the Citation II uses conventional gyros for the flight instruments then the weather radar transceiver would need its own gyro. The system on most commercial aircraft is linked into the IRS databus to get this data but if the Citation II doesn't have an IRS system then I guess it must have its own gyro in the transceiver, which would explain the cylindrical objects on top of the box.



Quoting Mr Spaceman (Reply 16):
Also guys, I don't understand why a weather radar transceiver that isn't linked to an IRS needs a mechanism that performs "Ridgidity In Space" (a gyro). Can the reason be briefly explained, or is it a way more complicated system than a gyro in a Artificial Horizon, HSI, or Turn/BanK Indicator?

Some of you guys spend too much time with the good stuff, you need to hang around in GA a bit and see aeroplanes built to a price without all the fancy gear  Wink The two units are Directional/Horizontal Gyros (made by Sperry by the looks of them) and are not used by the radar; they appear to be hooked up together because their wiring looms are all bundled together for routing aft into the cockpit.
A weather radar receives a signal from a Vertical/Attitude Gyro for stabilisation, usually only the roll signal but sometimes the pitch signal as well. Briefly, the radar uses the signal/s to adjust the scanner tilt when the aircraft is in a bank or is climbing/descending, so that the radar is still scanning horizontally at the degree of tilt selected by the crew. Basically, if the a/c is rolled left and there was no stabilisation, then the left part of the radar scan would be sweeping the ground and the right part of the scan would be sweeping space. With stabilisation, the scanner is tilted upwards during the left part of the scan and gradually tilts through neutral at the centre of the scan them gradually tilts down during the RH scan; if you could look at the scanner plate when the a/c was rolled it would appear to be horizontal throughout the sweep. Older radars with parabolic scanners will either tilt the dish or the centre horn, depending on type.
Aircraft without a remote Vertical Gyro usually have the stabilisation signal provided by the Artificial Horizon or don't have stabilisation. Some a/c e.g. some of the Metro 23s I have worked on, have a VG fitted whose sole purpose is to provide radar stabilisation.
You could probably have INS/IRS fitted to your Citation as an option, but I imagine that it would prove to cost a significant percentage of the overall price of the a/c, and it doesn't really need it anyway. The only GA-type a/c I have ever seen with Inertial Nav fitted, are a couple of King Airs that are used for Navaid calibration in this country.
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Mr Spaceman
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RE: What's This Bizjet Part Behind The Skin For?

Wed Jun 15, 2005 11:45 pm

Hello OzLAME.

Quoting OzLAME (Reply 17):
The two units are Directional/Horizontal Gyros (made by Sperry by the looks of them) and are not used by the radar; they appear to be hooked up together because their wiring looms are all bundled together for routing aft into the cockpit.

Yeah, those two round objects sure did look to me like they were connected to the radar dish. Thanks for letting us know that they're Directional/Horizontal Gyros instead.

Thank You Sir, for your excellent detailed info about the different ways a weather radar dish can be stabilized during changes in the aircraft's attitude. It's much appreciated. Big grin

Chris  Smile
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