AM I THE ONLY ONE THIS BOTHERS

[prunehead]

An extract from AAC 1-119 from the Civil Aviation Safety Authorities website. I just can't believe this is for real. I also posted this in Dununda, but I dont think the largely pilot following there quite realised how truley STUPID the idea it is to introduce water to an aircraft fuel tank at any time, least of all at maintenance http://www.pprune.org/ubb/NonCGI/frown.gif


Description of Problem

Aircraft may not have suitable water drain facilities. Water drain samples taken on daily flights may therefore not be representative of fuel in the aircraft, which could result in corrosion of vital fuel system components.

Recommended Continuing Maintenance Actions

The fuel system must be inspected at every 100 hour maintenance action. Should this inspection reveal evidence of water remaining in the fuel system, maintenance staff should test the fuel system for continuing compliance with the basis of certification, as described above.

One way to test the water drain facilities is to add a small measured amount of water into a fuel tank while the aircraft is on a level surface and the aircraft is in the normal ground attitude. The same amount of water should then move to the tank sump, and be drained from the aircraft. Any unexpected missing amount of water is evidence that the fuel system does not meet the drain criteria.

The water added must be clean; normal drinking water is adequate. The amount of water added should be appropriate to the tank size, and not exceed the minimum sump capacity, 400 ml. The water should be added while the tank is free of fuel.

Care must be taken, subsequent to this test, to ensure that the fuel tank is thoroughly dried prior to being refuelled and entering service.


If I read this correctly, they want us to empty aircraft fuel tanks at 100 hrly intervals, put miniscule amounts of water in them, see if it comes out, then dry the tanks out and return them to service if all the water by magic comes out without the lubricative and surface tension reduction effects of having fuel in the tanks !!

Lets all add two days to the cost and time of a standard 100 HRLY to do this, coupled with the DANGER of adding water to an aircraft fuel tank. Let alone the fact that FEW AIRCRAFT WILL PASS WITHOUT FUEL IN THE TANKS. Note that the requirement doesn't specify a method of determining how a maintenance organisation shall determine wheter a tank is dry before returning it to service!!

Note that the requirement does not also clearly specify in any discernable manner how the amount of water tested and removed from a 747 would differ from a cessna 441. Whilst it says proportional to, it does not quantify the statement.

If I add 400 Ml of water to a 747 tank, how much in reality will I get at the drain? The answer is that it will depend on where I add it to the tank, and how long i can wait for it to get there.

The AAC suggests further that if more than reasonably suspected goes missing that action must be taken. Please tell me with reference to the extreme example above what constitutes an unsuspected amount, and define it for each aircraft.


Then again SPARE ME. The whole idea of adding water to fuel tanks of aircraft during maintenance is absurd isnt it?

[Genghis the Engineer]

At first sight it didn't worry me too much, then thinking about it...

(1) Any alcohol content in the fuel (and there usually will be some) and much of the water will be absorbed by the fuel - potentially giving problems in flight.

(2) If the above happens, how do you know if it's a drain system fault or effects of the fuel.

(3) I'll bet that without agitating the aircraft (which presumably means flying it) at-least some water will sit in a corner of the tank without making it initially to the sump and drain.

(4) It is a rather glib assumption that all aircraft will meet the modern 400ml minimum sump size.

Overall, I can see some little sense in the idea of the test, but the practice does leave rather a lot to be desired.

Incidentally I was very involved in the decision to approve unleaded MOGAS for use here in the UK. As part of the exercise, the CAA tested various brands of fuel by mixing 50:50 fuel/water, agitating it in a jar, and waiting for it to settle. In one brand they actually ended up with more water than they started - they never did get to the bottom of why, but it would really bugger this CASA test method!

Regards,

G

[prunehead]

And how about the day and a half that it would take to empty tanks, add water, remove water, dry tanks, and refill tanks. Yeah I can see bugsmasher industry affording this little number!!

[the_toolman]

This maintenance practice does seem a little strange, probably thought up by someone wearing a suit in a nice warm office who actually didn't think about the labour involved by introducing this check.
The frequency of this check also puzzles
me. The frequency suggests that there must be a lot of reported problems with water ingress and or corrosion in the fuel system
although in my career I have yet to encounter such problems.

As for using water in the fuel tanks during maintenance I must admit on our yearly inspections of the fuel tanks in our aircraft(helicopters), once all the sump pads have been removed we use warm water mixed with Lux flakes to wash out the tanks. I don't know about you but even with breathing gear on I don't fancy spending a shift in a tank with all those fumes. It doesn't take all that long with proper ventilation and a few rags for the tanks to be completely dry.(The tanks are washed rather than flooded before you all fall off your chairs in aghast!!).

Just for info our aircraft do around 100hrs every 2.5 to 3 weeks and they seem to spend more time in the hanger on check than they do on the line earning us money.

[spannerhead]

If I knew how to link you direct, I would have done! I don't! So I have copied and pasted the entire article. (at least read my comments at the end).
Here we go!!!

Airworthiness Articles
AAC 1-119 Water Drains in Aircraft Fuel Systems 5/2001

Background

Water in the fuel system of an aircraft can cause corrosion of components in the fuel system and interrupt the correct operation of aircraft engines. Water can enter directly with fuel, via an unserviceable fuel cap, or breathing of air in the tanks due to changes in outside air temperature or the aircraft ascending and descending. Aircraft are designed to have this water safely drain from the aircraft. The current standards are:

FAR 23.971 Fuel tank sump.

(a) Each fuel tank must have a drainable sump with an effective capacity, in the normal ground and flight attitudes, and

(b) Each fuel tank must allow drainage of any hazardous quantity of water from any part of the tank to its sump with the aircraft in the normal ground attitude.

FAR 23.999 Fuel System Drains. There must be at least one drain to allow safe drainage of the entire fuel system with the aircraft in its normal ground attitude.

Previous Australia certification standards, such as CAO 101.22 para 3.2(1), included similar requirements. All aircraft certificated for operation in Australia are therefore required to have suitable water drain facilities.

Unfortunately, experience during the AVGAS fuel crisis demonstrated that some aircraft do not have satisfactory water drain facilities. Also, there is evidence that some fuel tanks provided as spares for Tiger Moth aircraft do not have suitable water drain facilities. Finally, Transport Canada FEED-BACK 3/4/2000 noted corrosion problems they have recorded due to the presence of water in fuel.

Description of Problem

Aircraft may not have suitable water drain facilities. Water drain samples taken on daily flights may therefore not be representative of fuel in the aircraft, which could result in corrosion of vital fuel system components.

Recommended Continuing Maintenance Actions

The fuel system must be inspected at every 100 hour maintenance action. Should this inspection reveal evidence of water remaining in the fuel system, maintenance staff should test the fuel system for continuing compliance with the basis of certification, as described above.

One way to test the water drain facilities is to add a small measured amount of water into a fuel tank while the aircraft is on a level surface and the aircraft is in the normal ground attitude. The same amount of water should then move to the tank sump, and be drained from the aircraft. Any unexpected missing amount of water is evidence that the fuel system does not meet the drain criteria.

The water added must be clean; normal drinking water is adequate. The amount of water added should be appropriate to the tank size, and not exceed the minimum sump capacity, 400 ml. The water should be added while the tank is free of fuel.

Care must be taken, subsequent to this test, to ensure that the fuel tank is thoroughly dried prior to being refuelled and entering service.

Corrective Action

Correction of the problem may entail smoothing the surface of bag tanks, or ensuring the aircraft fuel system conforms to the manufacturer’s requirements, or installation of a modification to incorporate improved drain points. A number of aircraft have SBs available to install extra drain points. Should the aircraft manufacturer not have a suitable SB available, it may be necessary to develop an approved modification for the aircraft.

If the test demonstrated that gentle rocking of the wings was necessary to move all water in the fuel tank to the drains, the aircraft owner/operator should be informed of procedures necessary to completely drain the fuel tanks of residual water. It may also be necessary to confirm that the pilot/operator is aware of requirements in CAO 20.2, Air Service Operations Safety Precautions Before Flight, to conduct regular tests for the presence of water in the fuel.

Read it all???

Because the article mentions AVGAS I think that the originator is talking about small piston engined a/c. Still a rather impractacle check to carry out on a cessna each 100 hours. If drains are checked on a regular basis then water should not present a problem. The article is talking about the design of the tank trapping water in areas where it will not migrate to the lowest level...ie the drains. Thats something for the manufacturer to sort out.