Brian,
Posted further below, for your convenience, is what the FAA has to say about the integral (wet wing) tank of the Cessna’s.
In the integral fuel tank the members that form the wing, spars, ribs, and hat channels where they intersect can act as damns preventing water from reaching the sump drains. Like the rubber wrinkles in Cessna rubber bladder fuel tanks prevented water from reaching the sump drain, now we have fixed rigid metal wrinkles in the integral fuel tank possibly preventing water from reaching the sump drain.
Additionally, sealant used to seal the wing tank (integral, wet wing) can also act as damns. Futhermore if the sump drain itself is not on actual tank bottom positive detection of water may be difficult.
Ask yourself this question. How often do you see water in your sump cup during the preflight of your aircraft?
In my opinion all general aviation aircraft are subject to water in the fuel tanks despite any and all attempts at prevention. Water may enter a aircraft fuel tank in many ways. Rain while the aircraft sits on the ground, washing the aircraft, condensation, bad fuel from an FBO, sabotage, and free water that is contained in fuel from the manufacturer.
If you see water in your sump cup often then your fuel system may be working as certified. If you are not seeing water in your sump cup it could mean your fuel system is not working as certified.
A simple test of a few ounces of red dyed water into your fuel tank and positive evidence of it at the sump drain and the ability to eliminate the same amount you just poured in will tell you if the aircraft fuel system offers positive detection of fuel contamination. Responsibility for the airworthiness and safety of your aircraft is the sole responsibility of the owner/operator.
I am not suggesting that Cirrus aircraft have a problem with their integral fuel tanks. I just asked the following question.
Has anyone to your knowledge performed a simple test on the integral fuel tank of the Cirrus to insure that all hazardous quantities of water can be positively detected and eliminated during the preflight of the aircraft?
Brian, everything you would ever need to know about the subject of positive detection of fuel contamination is on my non-commercial research only website. A complete read of the site, pictures of water inside the integral fuel tank, and documentation of water tests over many decades is all available at a click of your mouse.
Best Regards,
Robert E. Scovill, Jr.
http://sumpthis.com/
Memorandum
Subject:
Information: FAA Safety Recommendations 99.283 and 99.284
Date: March 10, 2000
From:
Associate ACO, Manager Airframe and Services ACE-118W
Reply to J. D. Janusz
Attn. of:
316-946-4148
To:
Manager, Recommendation & Quality Assurance Division, AAI-200
We have completed our review of the subject recommendations. The subject recommendations cited an example of a Cessna Model 172P that had experienced one incident of a rough running engine and 3 separate in-flight shutdowns, which resulted in forced landings. This particular airplane was equipped with the original standard single wing fuel drain, located in the aft inboard section of each integral wing fuel tank (1 LH & 1 RH). Following the second in-flight shutdown, this operator had Cessna Service Kit SK182-100 installed, which added 4 additional drains at various locations throughout each integral wing tank. The operator experienced an additional in-flight engine shutdown following the kit installation, and has since determined his airplane to be unairworthy, and identifies it as such.
At this time the Wichita Aircraft Certification Office (ACO) has determined the following:
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Safety recommendation 99.283: We have reviewed the water/contamination egress capability of the Cessna model 172P, and find that it is not adequate. Our findings indicate that this operator’s airplane was designed and manufactured in such a manner as to not provide adequate water/contamination egress capability. Based on our review, we have determined that other Cessna high wing airplanes use a similar design and construction method for their integral wing fuel tanks. Therefore, we believe this condition may exist on other integral fuel tank equipped Cessna high wing airplanes with gravity feed fuel systems.
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Safety recommendation 99.284: We have reviewed the effectiveness of Cessna Service Kit SK 182 -100 and found that it is not adequate to perform it’s intended function of assisting in the detection and removal of water and/or contaminants in the integral wing fuel tanks when the airplane is in a normal ground attitude.
Based on our findings, the Wichita ACO will take the following action with Cessna
Aircraft Co:
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Advise them we have determined their design does not comply with the requirements of CAR 3.444 for the model 172P, when equipped with integral fuel tanks.
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Advise them we have identified an unsafe condition, which exists on the model 172P aircraft equipped with integral fuel tanks, and that this condition is likely to exist on other airplanes of the same type design.
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Advise them that we will be taking Airworthiness Directive action based on the above findings.
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Advise them the Administrator has determined that design changes are necessary to correct the unsafe condition, and requests their submittal of appropriate design changes for FAA approval within 30 days.
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Advise them we believe this condition may exist on all Cessna high wing integral fuel tank equipped airplanes, and request their identification of applicable models and serial numbers and submittal of appropriate design changes for each model for FAA approval within 60 days.
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Advise them that we will be making a Specific Finding to the requirements of 14 CFR part 23.971 on the current Model 182T and T182 programs.
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Advise them we will request a full review of compliance substantiation for the model 172, 182 and 206 series airplanes manufactured since the restart of production (type certificated since 1996), with respect to the requirements of 14 CFR part 23.971.
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Take any other action deemed appropriate based on the above actions.
We thank you for bringing this situation to our attention and trust that our action plan is considered sufficient to close the subject safety recommendations.
If you have any questions or need additional information regarding these issues, please contact Mr. Jeff Janusz, ACE-116W at (316) 946-4148.
David Ostrodlea
For
Ronald K. Rathgeber