Fuel filter

[Tom Baker]

50 minutes ago, FlyingMonkey said:

Another data point:

I replaced my plastic fuel filter at about 200hrs with metal.  Since I have followed the checklist, which says inspect at 200hr.  I just finished my annual and inspected it, and there were a few sand-like grains in it, and one black fleck like paint maybe 1mm across.  I do not pre-filter my mogas like some do.

With this level of fouling, the filter i.s probably good for 500-1000 hours, but of counse one wants to be conservative.  I think 200hr inspections are a good balance between being often enough to catch problems, and not too often to make maintenance induced failures more likely.

I’m not making any statements on what’s legal for SLSA.  I fly an ELSA, so my burden is just to certify the airplane is in condition for safe operation.  I encourage the SLSA drivers to get the definitive answer from FDUSA om this, since it seems there’s confusion.

Andy, Where does it say inspect every 200 hours? The copy of the CTSW MM I have says "Change the fuel filter at least every 200 hours". It also includes the inspection for the filter in 6.8.3 of the MM.

[Doug G.]

1 hour ago, Tom Baker said:

For any item on the checklist it is a requirement to check something. It may be as simple as checking compliance, or there may be an inspection spelled out in the MM. The notes within the checklist are there to guide you along the way. However you need to look at more than just the checklist. You also need to look at the text in the MM. That is where you really find out what you need to inspect.

For the wing I check the log books and see if it was done last year or has accumulated 600 hours since the last inspection. If it has been more that 600 hours or 2 years I do the inspection. I then mark off the appropriate box.

For the fuel filter the 200 hour requirement noted in the checklist was for replacement of a life limited part not the inspection. The inspections required is in the MM under 6.7.3, and it still applies. The SB changes the requirement for replacement every 200 hour, but it does not remove the requirement for the inspection. That is spelled out in the SB.

 

I seem to be missing something here.
The MM says to "Change fuel filter behind lower instrument panel at least every 200 hrs."
The SB 2.7 says, "Maintenance intervals of the new fuel filter are as required by your maintenance manual for the initial fuel filter with plastic housing."

As I read those, the metal filter is to be "changed" every 200 hours, not just inspected or cleaned.
Is that how you read it Tom? Is there a superseding SB I am missing?

[Tom Baker]

Doug, This is the inspection as called out in the MM. The image didn't copy, but it is a picture of the old plastic fuel filter. The highlighted in red is the inspection that is required per the checklist. The bold at the bottom is the required replacement of the old plastic filter. This is the statement that is added to the inspection checklist for the fuel filter. Before the SB you were to adhere to both the inspection and replacement requirements. After the replacement the inspection requirements still apply.

6.7 Fuel Filter

6.7.1 Type of Maintenance

Line

6.7.2 Minimum Level of Certification

Repairman, Light Sport Aircraft-Maintenance (RLSA-M) or higher.

6.7.3 Procedure

Fig. 5

Inspect for:

1. Leaks at joint of the connector (Fuel Filter 5/16’’, Fig. 5, unit 1) and hose (Fuel tube DIN 73379,

7.5x13.0). Tighten the clamp Fig. 5, unit 2), if necessary;

2. Filter body integrity.

3. Foreign objects inside the filter.

The filter must be replaced latest every 200h, or earlier on condition.

[Tom Baker]

38 minutes ago, Doug G. said:

I seem to be missing something here.
The MM says to "Change fuel filter behind lower instrument panel at least every 200 hrs."
The SB 2.7 says, "Maintenance intervals of the new fuel filter are as required by your maintenance manual for the initial fuel filter with plastic housing."

As I read those, the metal filter is to be "changed" every 200 hours, not just inspected or cleaned.
Is that how you read it Tom? Is there a superseding SB I am missing?

2.4 of the SB says to gain access to the fuel filter just like is done in every 100 hour inspection. Why would you need to gain access to the filter in every 100 hours for inspection if it only needed to be inspected every 200 hours?

[FlyingMonkey]

1 hour ago, Tom Baker said:

Andy, Where does it say inspect every 200 hours? The copy of the CTSW MM I have says "Change the fuel filter at least every 200 hours". It also includes the inspection for the filter in 6.8.3 of the MM.

I mentioned the checklist not the MM says 200hr, IIRC.  That’s what I’ve been going by.

[Tom Baker]

3 minutes ago, FlyingMonkey said:

I mentioned the checklist not the MM says 200hr, IIRC.  That’s what I’ve been going by.

The checklist does say 200hr, but that is for replacement of the filter not the inspection.

[Roger Lee]

5 minutes ago, Tom Baker said:

The checklist does say 200hr, but that is for replacement of the filter not the inspection.

Now you know why it needs to be fixed in the manual and the checklist. Nobodies feet could be held to the fire because each contradicts and fails to be specific and is out of date with current use.

 

So the bottom line for all is inspect it at 100 hrs. if you want or 200 hrs. or throw that re-usable metal filter away and put a new one in as per the list. It all works. Pick your poison.

[Doug G.]

So here is where I end up. I agree with both of you because there is no clarity here. FD has done a poor job of revising documents over the years. 

I cannot, without some sort of strange logic gymnastics get the checklist, MM instructions and the SB to make any sort of sense. There are about three different ways you can approach this. The most conservative would be to inspect at 100h and replace the metal filter at 200h. 

We need input from FD. Maybe a maintenance difficulty report...if they don’t end up in a black hole. That would put the ball legally in their court. Arian could also be asked, but without something in writing it is unlikely to have legal standing.

IMO FWIW

[Roger Lee]

2 hours ago, Doug G. said:

So here is where I end up. I agree with both of you because there is no clarity here. FD has done a poor job of revising documents over the years. 

I cannot, without some sort of strange logic gymnastics get the checklist, MM instructions and the SB to make any sort of sense. There are about three different ways you can approach this. The most conservative would be to inspect at 100h and replace the metal filter at 200h. 

We need input from FD. Maybe a maintenance difficulty report...if they don’t end up in a black hole. That would put the ball legally in their court. Arisen could also be asked, but without something in writing it is unlikely to have legal standing.

IMO FWIW

Exactly. What he said. 

[Doug G.]

Sorry...Arian got autocorrected.

[Tom Baker]

14 hours ago, Doug G. said:

So here is where I end up. I agree with both of you because there is no clarity here. FD has done a poor job of revising documents over the years. 

I cannot, without some sort of strange logic gymnastics get the checklist, MM instructions and the SB to make any sort of sense. There are about three different ways you can approach this. The most conservative would be to inspect at 100h and replace the metal filter at 200h. 

We need input from FD. Maybe a maintenance difficulty report...if they don’t end up in a black hole. That would put the ball legally in their court. Arian could also be asked, but without something in writing it is unlikely to have legal standing.

IMO FWIW

Doug, the thing to remember is the 200 hour figure on the checklist was never for inspection, but for replacement of the filter. The inspection requirements were to be met at the 100hr/annual inspection intervals. The only ambiguity for me is the fact that there is nothing in the SB stating the new filter does not need replaced at the 200 hour interval, though the SB does provide details on cleaning the filter where that was not an option for the plastic filter. I also found this little jewel in the MM in regards to the filter.

8. Inspect the fine filter for cleanliness (Fig. 1, item R; Fig. 6, C9997813G Fuel Filter 5/16’’) each

time the middle panel КВ1081300 (Fig. 1) of the instrument board is removed (see chapter 6.10

for details).

[Tom Baker]

Here is another path from the maintenance manual and checklist that indicate the fuel filter is supposed to be checked at the annual condition inspection.

From the checklist,

Instrument board inside and panels’ backside. Remove all

instrument panels and inspect all lines, wires, control cables, hoses,

instruments, and so on, for chafing, any interference, and loose or

stressed connections. Inspect firewall structure for cracks, debonding,

and general condition.

From the maintenance manual chapter 6 fuel system, 6.4 general inspection.

8. Inspect the fine filter for cleanliness (Fig. 1, item R; Fig. 6, C9997813G Fuel Filter 5/16’’) each

time the middle panel КВ1081300 (Fig. 1) of the instrument board is removed (see chapter 6.10

for details).

It looks like if the panel is removed as required by the checklist for inspection, then the fuel filter must be inspected.

[Doug G.]

2 hours ago, Tom Baker said:

Doug, the thing to remember is the 200 hour figure on the checklist was never for inspection, but for replacement of the filter. The inspection requirements were to be met at the 100hr/annual inspection intervals. The only ambiguity for me is the fact that there is nothing in the SB stating the new filter does not need replaced at the 200 hour interval, though the SB does provide details on cleaning the filter where that was not an option for the plastic filter. I also found this little jewel in the MM in regards to the filter.

8. Inspect the fine filter for cleanliness (Fig. 1, item R; Fig. 6, C9997813G Fuel Filter 5/16’’) each

time the middle panel КВ1081300 (Fig. 1) of the instrument board is removed (see chapter 6.10

for details).

Which comes back around to what I have been questioning all along...what do you do with the ambiguity? Do you replace the metal filter every 200 hours? (He asked once again.)
The item in 6.4.3 was obviously written when all you needed to do was look at the filter, not disassemble it. When you are dealing with avionics, flaps or the starter switch do you follow the filter inspection procedure?
It is not good to have a legally enforceable document with such vagueness.

[Doug G.]

5 minutes ago, Tom Baker said:

Here is another path from the maintenance manual and checklist that indicate the fuel filter is supposed to be checked at the annual condition inspection.

From the checklist,

Instrument board inside and panels’ backside. Remove all

instrument panels and inspect all lines, wires, control cables, hoses,

instruments, and so on, for chafing, any interference, and loose or

stressed connections. Inspect firewall structure for cracks, debonding,

and general condition.

From the maintenance manual chapter 6 fuel system, 6.4 general inspection.

8. Inspect the fine filter for cleanliness (Fig. 1, item R; Fig. 6, C9997813G Fuel Filter 5/16’’) each

time the middle panel КВ1081300 (Fig. 1) of the instrument board is removed (see chapter 6.10

for details).

It looks like if the panel is removed as required by the checklist for inspection, then the fuel filter must be inspected.

Now you are just trying to prove the unprovable. If I take your word on this I need to go out an buy a plastic filter, put it behind the panel so I can inspect the filter (C9997813G) when I remove the panel? That part is by SB no longer a part of my plane...NA by part number. lol

[Roger Lee]

The aluminum filter is re-usable and there is need need to replace. This is just poor documentation on FD's part.

[Tom Baker]

1 hour ago, Doug G. said:

Now you are just trying to prove the unprovable. If I take your word on this I need to go out an buy a plastic filter, put it behind the panel so I can inspect the filter (C9997813G) when I remove the panel? That part is by SB no longer a part of my plane...NA by part number. lol

Doug, the point I have been trying to make all along, and I think I have, is that the 200 hour requirement is not for the inspection it is for replacement of the plastic filter.

[FlyingMonkey]

I am in agreement with Tom.  If you look at the MM and checklist together, inpection is required every annual/100hr and replacement at 200hr with the old plastic.

I have been doing it wrong, but I do think 100hr is too often.  It's easy to harm the o-ring or a hose, and the chances of finding a dangerously clogged filter in 100hr are about nil.

Perhaps this could be adressed with FD and changed...

[Tom Baker]

6 minutes ago, FlyingMonkey said:

I am in agreement with Tom.  If you look at the MM and checklist together, inpection is required every annual/100hr and replacement at 200hr with the old plastic.

I have been doing it wrong, but I do think 100hr is too often.  It's easy to harm the o-ring or a hose, and the chances of finding a dangerously clogged filter in 100hr are about nil.

Perhaps this could be adressed with FD and changed...

The problem is you don't know if the filter is dangerously clogged unless you look at it. Checklist are full of items you check for and hope to never find an issue, but you need to check them anyway. O-rings can be changed every inspection, that is not a big deal. Depending on the installation I often replace a small section of hose anyway when I inspect the filter, because it makes the job easier.

[Doug G.]

The problem with this discussion is that the MM is not clear and all of us are interpreting it as if it is. It does not define when it is talking about the metal filter and when it is talking about the metal one. We are all interpreting what we see by saying that one part or other does or does not apply based, not on what it says, but what we think it should. It should not work that way.

I will do 100 hr checks, but I don’t actually see it saying that clearly states that.

 I think all that can be said has been. I’m done.

[Tom Baker]

The only thing that isn't clear and spelled out is whether or not the replacement of the fuel filter per the SB removes the requirement to change the filter at least every 200 hours. I think common sense and the maintenance instructions on servicing the filter in the SB pretty much indicate that the metal filter does not need changed every 200 hours. Changing it would serve no useful purpose like it did with the plastic filter.

[procharger]

If you are getting good fuel flow from the gascolator filter should be ok I think.    spelling

[Roger Lee]

I talked to Tom P. at FD. He said just inspect it it's reusable. There is no 200 hr. replacement. 

[Doug G.]

16 minutes ago, Roger Lee said:

I talked to Tom P. at FD. He said just inspect it it's reusable. There is no 200 hr. replacement. 

Which, of course, is what common sense says, but does common sense hold up in the eyes of the law or the FAA? FD should fix the MM. 
Thanks, Roger.
Yeah, I know I said I was done, but I thought it was common sense to make one more comment. 

[FlyingMonkey]

3 hours ago, Tom Baker said:

The problem is you don't know if the filter is dangerously clogged unless you look at it. Checklist are full of items you check for and hope to never find an issue, but you need to check them anyway. O-rings can be changed every inspection, that is not a big deal. Depending on the installation I often replace a small section of hose anyway when I inspect the filter, because it makes the job easier.

Agreed, but by that reasoning you don’t know if your pistons are cracked without borescoping them before each flight.  You have to play the odds with your maintenance, and IMO the chances of a fully clogged filter within 200hr is extremely low.  I think a 200hr check is reasonable; 100hr is a little OCD.

I agree on the hose, I cut it down and then remove the stub from the filter.  Much easier.

[Tom Baker]

1 hour ago, FlyingMonkey said:

Agreed, but by that reasoning you don’t know if your pistons are cracked without borescoping them before each flight.  You have to play the odds with your maintenance, and IMO the chances of a fully clogged filter within 200hr is extremely low.  I think a 200hr check is reasonable; 100hr is a little OCD.

I agree on the hose, I cut it down and then remove the stub from the filter.  Much easier.

I don't think bore scoping the pistons is on the checklist. I have never found any significant metal on a magnetic plug, should I based on that not check the magnetic plug at the recommended interval? I have not found any metal in a Rotax oil filter, should I stop cutting them open? The checklist provides a minimum of what should be check, and in my opinion the inspection intervals on the checklist should be followed.