Fuel Bladder

sxauer · February 18th, 2003, 14:33

Can someone point out the advantages of using fuel bladders as opposed to fuel tanks? When flying the old 172s, I only had 3 sumps to drain durring my preflight, but when I fly the new SPs I have to drain 13 sumps. Why the change to fuel bladders instead of the integral fuel tanks? Weight? Cheaper? Thanks for the input....

-shaun

pilot602 · February 18th, 2003, 14:37

[ QUOTE ]
When flying the old 172s, I only had 3 sumps to drain durring my preflight, but when I fly the new SPs I have to drain 13 sumps.

[/ QUOTE ]

<font color="purple"> Lawsuits. </font>

sxauer · February 18th, 2003, 14:45

lawsuits? I'm not a mechanic, but it would seem to me that a tank would be much more safe than a bladder as far as trapping water in the tank goes because the bladder could develop a wrinkle or somthing that would prevent water from reaching the sump. I may be way off base here, so if I am wrong, somebody please let me know.

-shaun

aviator · February 18th, 2003, 15:01

I assumed Cessna added all those extra sumps for legal reasons as well.......

Mahesh · February 18th, 2003, 15:19

I am not knowledgable in construction but is it easier or cheaper on the assemply line to use bladders?

Mahesh

pilot602 · February 18th, 2003, 15:50

You have two, seperate issues here.

The fuel bladder/intergral tanks are one issue.

The number of sumps are a second.

Apparently, the reason Cessna now has 13 sumps on the new 172s (I flew Rs for my primary and am quite familar with all 13 of 'em!) is because of lawsuits in the late '60s and primarily in the '70s. Morons ... sorry "pilots," would head out to their bird, hop in, turn the engine over and fly away, never having sumped the fuel tanks. Then - surprise, surprise - when the engine would choke due to water in the line the "pilot" would invaribly bungle the "emergency" landing and in turn he or she would sue Cessna citing that they "had sumped the aircraft" but the "sumps didn't get it all." The lawsuits got so bad that most GA manufacturers quit making small GA aircraft which is why all of us are flying around in old beat up tin cans.

As a precautionary measure the new Cessnas have an insane number of sumps partly as legal protection against would be morons.

The tank/bladder issue is an engeneering/manufacturing measure. Each has it's merits and drawbacks but I'm not sure this change is directly related to the number of sumps or if they even did, infact, change from one storage method to the other.

Ophir · February 18th, 2003, 19:28

I have no idea if this is a reason but it seems plausible:

With bladders, in the event that your fuel vent became clogged, the bladder would then become void of all fuel. On the other hand, if flying a fuel tank, if the fuel vent became clogged, then a vacuum could set up inside the tank and eventually arrest fuel flow to the engine.

Additionally, when sumping the fuel you are checking for, among other things, H20. If a bladder colapses, the volume of air in the bladder it able to get smaller and thus deminish the propensity for H20 vapors to be in the air and therefore eventually condense into the fuel.

February 18th, 2003, 14:33	#1
sxauer Junior Member Join Date: Sep 2000 Location: Louisiana Posts: 124	Fuel Bladder Can someone point out the advantages of using fuel bladders as opposed to fuel tanks? When flying the old 172s, I only had 3 sumps to drain durring my preflight, but when I fly the new SPs I have to drain 13 sumps. Why the change to fuel bladders instead of the integral fuel tanks? Weight? Cheaper? Thanks for the input.... -shaun

February 18th, 2003, 14:37	#2
pilot602 Old Skool Join Date: Oct 2001 Location: who haa Posts: 3,750	Re: Fuel Bladder [ QUOTE ] When flying the old 172s, I only had 3 sumps to drain durring my preflight, but when I fly the new SPs I have to drain 13 sumps. [/ QUOTE ] <font color="purple"> Lawsuits. </font>

February 18th, 2003, 14:45	#3
sxauer Junior Member Join Date: Sep 2000 Location: Louisiana Posts: 124	Re: Fuel Bladder lawsuits? I'm not a mechanic, but it would seem to me that a tank would be much more safe than a bladder as far as trapping water in the tank goes because the bladder could develop a wrinkle or somthing that would prevent water from reaching the sump. I may be way off base here, so if I am wrong, somebody please let me know. -shaun

February 18th, 2003, 15:01	#4
aviator Senior Member Join Date: Jul 2001 Posts: 385	Re: Fuel Bladder I assumed Cessna added all those extra sumps for legal reasons as well.......

February 18th, 2003, 15:19	#5
Mahesh Senior Member Join Date: Mar 2001 Location: Northern Hemisphere Posts: 1,311	Re: Fuel Bladder I am not knowledgable in construction but is it easier or cheaper on the assemply line to use bladders? Mahesh

February 18th, 2003, 15:50	#6
pilot602 Old Skool Join Date: Oct 2001 Location: who haa Posts: 3,750	Re: Fuel Bladder You have two, seperate issues here. The fuel bladder/intergral tanks are one issue. The number of sumps are a second. Apparently, the reason Cessna now has 13 sumps on the new 172s (I flew Rs for my primary and am quite familar with all 13 of 'em!) is because of lawsuits in the late '60s and primarily in the '70s. Morons ... sorry "pilots," would head out to their bird, hop in, turn the engine over and fly away, never having sumped the fuel tanks. Then - surprise, surprise - when the engine would choke due to water in the line the "pilot" would invaribly bungle the "emergency" landing and in turn he or she would sue Cessna citing that they "had sumped the aircraft" but the "sumps didn't get it all." The lawsuits got so bad that most GA manufacturers quit making small GA aircraft which is why all of us are flying around in old beat up tin cans. As a precautionary measure the new Cessnas have an insane number of sumps partly as legal protection against would be morons. The tank/bladder issue is an engeneering/manufacturing measure. Each has it's merits and drawbacks but I'm not sure this change is directly related to the number of sumps or if they even did, infact, change from one storage method to the other.

February 18th, 2003, 19:28	#7
Ophir Senior Member Join Date: Mar 2002 Location: was Ophir, CO, now in SLC! Posts: 1,477	Re: Fuel Bladder I have no idea if this is a reason but it seems plausible: With bladders, in the event that your fuel vent became clogged, the bladder would then become void of all fuel. On the other hand, if flying a fuel tank, if the fuel vent became clogged, then a vacuum could set up inside the tank and eventually arrest fuel flow to the engine. Additionally, when sumping the fuel you are checking for, among other things, H20. If a bladder colapses, the volume of air in the bladder it able to get smaller and thus deminish the propensity for H20 vapors to be in the air and therefore eventually condense into the fuel.

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