A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Piloting
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Bad fuel gauges?



 
 
Thread Tools Display Modes
  #61  
Old February 25th 08, 03:52 AM posted to rec.aviation.piloting
C J Campbell[_1_]
external usenet poster
 
Posts: 799
Default Bad fuel gauges?

On 2008-02-24 17:29:14 -0800, Jay Maynard
said:

On 2008-02-24, wrote:
No, I haven't just proclaimed that. Rather, I've explained in detail
why I think the gauges ARE useful, in a particular way, if they're
anything like the dozens of planes I've rented in various places. And
I've explained in detail why I think they're illegal otherwise, citing
specific regulations. (There may or may not be a "reality" that
illegal planes are common--but that doesn't change whether they're
illegal.) And CJ and I and others have given reasons that fuel gauges
are desirable for safety as well as legality.


You have not, however, explained why, since fuel gauge accuracy is
notoriously unreliable for good and sufficient reason, half the GA fleet or
more isn't grounded.

Your responses are all straight out of the book, with no grounding in the
real world.


I would have to see some actual evidence that half the GA fleet should
be grounded for inaccurate fuel gauges. In fact, I doubt if they are
nearly as inaccurate as you claim them to be. Blind belief in an
aviation legend is not real world experience.

Yes, I know fuel gauges can be inaccurate. But that does not mean that
they are always inaccurate, that they are totally unusable, or that
they only have to be accurate when they are empty. Assertions like that
are simply nonsense.

Airplane fuel gauges are generally accurate. Yes, they can be thrown
off by lack of maintenance, unusual attitudes, turbulence, and
malfunction. But those are the exceptions, not the rule. Flying with
malfunctioning fuel gauges can get your ticket pulled, whether you
think that is fair or not. Flying with a malfunctioning fuel gauge
simply because you think that is normal or that it is inaccurate anyway
is simply an excuse for poor piloting, poor maintenance, and general
laziness.
--
Waddling Eagle
World Famous Flight Instructor

  #62  
Old February 25th 08, 03:58 AM posted to rec.aviation.piloting
Bertie the Bunyip[_24_]
external usenet poster
 
Posts: 2,969
Default Bad fuel gauges?

C J Campbell wrote in
news:2008022418524316807-christophercampbell@hotmailcom:

On 2008-02-24 17:29:14 -0800, Jay Maynard
said:


I would have to see some actual evidence that half the GA fleet should
be grounded for inaccurate fuel gauges. In fact, I doubt if they are
nearly as inaccurate as you claim them to be. Blind belief in an
aviation legend is not real world experience.

Yes, I know fuel gauges can be inaccurate. But that does not mean that
they are always inaccurate, that they are totally unusable, or that
they only have to be accurate when they are empty. Assertions like
that are simply nonsense.

Airplane fuel gauges are generally accurate. Yes, they can be thrown
off by lack of maintenance, unusual attitudes, turbulence, and
malfunction. But those are the exceptions, not the rule. Flying with
malfunctioning fuel gauges can get your ticket pulled, whether you
think that is fair or not. Flying with a malfunctioning fuel gauge
simply because you think that is normal or that it is inaccurate
anyway is simply an excuse for poor piloting, poor maintenance, and
general laziness.


I'd agree with al of this except the part that says they're generally
reliable. I've seen lots of them that aren't. Lots and lots!

Bertie
  #63  
Old February 25th 08, 05:57 AM posted to rec.aviation.piloting
[email protected]
external usenet poster
 
Posts: 373
Default Bad fuel gauges?

The requirement for indications of a tank's fuel level (not just on
empty) is stated in 91.205b9, 23.1305a1, and 23.1337b.


Let me just quote these.

91.205, b9:
"(a) General. Except as provided in paragraphs (c)(3) and (e) of this
section, no person may operate a powered civil aircraft with a
standard category U.S. airworthiness certificate in any operation
described in paragraphs (b) through (f) of this section unless that
aircraft contains the
instruments and equipment specified in those paragraphs (or FAA-
approved equivalents) for that type of operation, and those
instruments and items of equipment are in operable condition."
....
(9) Fuel gauge indicating the quantity of fuel in each tank.

I did my primary training in a plane that had a right wing tank fuel
gauge that always showed less than "F" when the tank was completely
full. If the interpretation of the FAR is STRICT, I guess that means
my training was done illegally, because the gauge DID NOT indicate the
quantity of fuel in the right wing tank (ie, FULL). Rather, it
indicated less than full.

But the writing of the reg is not explicit (they get explicit in
1337b). To me it comes down to ramp checks, FAA enforcement, and case
law. I have never flown that aircraft to the end of its usable fuel,
so I don't if the aircraft I did my primary training in adheres to
1337b:

"(b) Fuel quantity indicator. There must be a means to indicate to the
flightcrew members the quantity of usable fuel in each tank during
flight. An indicator calibrated in appropriate units and clearly
marked to indicate those units must be used. In addition--
(1) Each fuel quantity indicator must be calibrated to read "zero"
during level flight when the quantity of fuel remaining in the tank is
equal to the unusable fuel supply determined under [Sec. 23.959(a);]"

So, what's the case history? How many pilots / mechanics have been
fined, had their certification suspended or even revoked because a
fuel gauge was shown to not indicate "the quantity of fuel in each
tank."

The FAA regs listed only speak to calibration when talking about zero
useable fuel. Nothing else.

If that's the only unambiguous calibration statement in the FARs then
I think that's because the FAA realizes fuel gauge accuracy is subject
to reasonable limitations. Why would they otherwise have us spend so
much time understanding calculated vs real fuel usage, especially
during cross country training for the private certificate? If gas
gauges were really accurate then the FAA wouldn't bug us so much about
learning to calculate and cross-check, and cruise charts wouldn't be
such a critical part of the POH. The recommended way and the way we
train is to KNOW YOUR AIRCRAFT through repeated measurement and cross-
checking the perf charts.

No FAA or other training manual says "Just check you gas gauge real
quick to see if you need to pull over for gas -- and make sure you
land and refuel when the idiot light comes on!"

Gas gauges provide solid value as indicators of possible leak
situations and when you are almost out (again, calibration is mandated
to be correct only at zero).

Lawyers specialize in writing that is crystal clear when they want it
to be, and subject to court judgement otherwise. I think the fuzzy
language the government lawyers used in crafting the regs around fuel
gauges was done on purpose.


  #64  
Old February 25th 08, 06:29 AM posted to rec.aviation.piloting
WJRFlyBoy
external usenet poster
 
Posts: 531
Default Fuel Quantity Measurement

On Sun, 24 Feb 2008 17:26:53 -0800, RST Engineering wrote:

a) floats inherently leak over time unless they are some light solid, and
then they have a tendency over decades to break down and saturate.


Kevlar?
--
Remove numbers for gmail and for God's sake it ain't "gee" either!
  #65  
Old February 25th 08, 02:59 PM posted to rec.aviation.piloting
[email protected]
external usenet poster
 
Posts: 156
Default Bad fuel gauges?

On Feb 24, 8:29*pm, Jay Maynard
wrote:
On 2008-02-24, wrote:
You have not, however, explained why, since fuel gauge accuracy is
notoriously unreliable for good and sufficient reason, half the GA fleet or
more isn't grounded.


Yes I've repeatedly explained that. What I keep pointing out is that
the gauges are typically at least accurate enough to alert you to a
large leak, which is a warning that your flow calculations cannot give
you. That makes the gauges useful (and operable), in a limited but
important way, and explains why they're required for airworthiness.

But as I have acknowledged, the flow calculations are typically much
more reliable than the gauges under NORMAL circumstances. That's fine--
the guages are just one part of how you're supposed to keep track of
your fuel.
  #66  
Old February 25th 08, 03:02 PM posted to rec.aviation.piloting
[email protected]
external usenet poster
 
Posts: 156
Default Bad fuel gauges?

On Feb 24, 8:06*pm, Clark wrote:
That said, how on Earth can fuel gauges be considered accurate? At the very
least one would have to specify attitude (which some gauges do but most
don't). Maybe there could be a calibration card for airspeed, weight, and
CG? Wouldn't that be fun?


The gauges are typically at least accurate enough to alert you to a
large leak, which is a warning that your flow calculations cannot give
you. That makes the gauges useful (and operable), in a limited but
important way, and explains why they're required for airworthiness.

As I have acknowledged, the flow calculations are typically much more
reliable than the gauges under NORMAL circumstances. That's fine--the
gauges are just one part of how you're supposed to keep track of your
fuel.
  #67  
Old February 25th 08, 03:10 PM posted to rec.aviation.piloting
[email protected]
external usenet poster
 
Posts: 156
Default Bad fuel gauges?

On Feb 24, 4:10 pm, Bob Noel
wrote:
In article ,
No. Cost is not part of the equation wrt reducing risk, at least as far
as the FAA is concerned. If you were an applicant and tried to get
an aircraft certified that didn't meet the standards in AC 23.1309 or
AC 25.1309 because it would cost too much, the FAA would deny
the application.


I see what you're getting at. Those ACs indeed specify a maximum
acceptable probability for e.g. a catastrophic failure, regardless of
the cost of keeping the probability within that bound. But that's
still consistent with my point about cost, for three reasons.

First, the decision where to set the acceptability threshold is
already informed by the FAA's knowledge of what threshold is
affordable. The ACs' acceptable probability of catastrophic failure,
especially for the less expensive classes of GA aircraft, is high
enough to allow many fatalities per year across the fleet. If much
higher safety were achievable at a reasonable cost, the FAA would
presumably have set the probability threshold lower.

Second, for the more expensive classes of GA aircraft, that threshold
IS set lower, by two or three orders of magnitude! Presumably, that's
in part because the bigger planes can afford to meet higher safety
standards--standards that would swamp the cost of the smaller planes.

Third, those ACs set a CEILING for acceptable failure probabilities.
Unless I've missed something, there's nothing in the ACs to prevent
the FAA from deciding that a particular item of safety equipment is
required for airworthiness, even if the absence of that equipment
would still leave the catastrophe probabilities within the standards
set by the ACs. And cost is surely a factor in making THOSE decisions.
(For example, if ADS-B technology cost $500,000 per plane, the FAA
would not be proposing to require it.)
  #68  
Old February 25th 08, 07:40 PM posted to rec.aviation.piloting
Maxwell
external usenet poster
 
Posts: 1,116
Default Bad fuel gauges?


wrote in message
...

The gauges are typically at least accurate enough to alert you to a
large leak, which is a warning that your flow calculations cannot give
you. That makes the gauges useful (and operable), in a limited but
important way, and explains why they're required for airworthiness.

Fuel gauges fail a lot more often than we develop significant leaks, and
fuel gauges will never be able to reassure you that you don't have small
leak causing an extreme fire hazard.

Hence, experience has taught all of us (including the FAA), that there are
much better ways to manage your fuel 99 and 44/100% of the time, than the
fuel gauges made possible by current technology.

Get over it!!

I can assure you:
if you get caught on a ramp check,
and they even notice a failed fuel gauge,
and are anal enough to stick you for it,
and they can prove that it didn't just happen,

It just wasn't your day to be flying, and you are probably damn lucky you
didn't actually get in the air.

These are the kind of days you get run over by an F-16, loose both mags over
water, stroke out, your dog leaves you, etc. You should actually be glad
you only got stuck with 90 day suspension for a bad fuel gauge.







  #69  
Old February 25th 08, 07:41 PM posted to rec.aviation.piloting
Maxwell
external usenet poster
 
Posts: 1,116
Default Bad fuel gauges?


wrote in message
...
On Feb 24, 4:10 pm, Bob Noel
wrote:
In article
,
No. Cost is not part of the equation wrt reducing risk, at least as far
as the FAA is concerned. If you were an applicant and tried to get
an aircraft certified that didn't meet the standards in AC 23.1309 or
AC 25.1309 because it would cost too much, the FAA would deny
the application.


I see what you're getting at. Those ACs indeed specify a maximum
acceptable probability for e.g. a catastrophic failure, regardless of
the cost of keeping the probability within that bound. But that's
still consistent with my point about cost, for three reasons.

First, the decision where to set the acceptability threshold is
already informed by the FAA's knowledge of what threshold is
affordable. The ACs' acceptable probability of catastrophic failure,
especially for the less expensive classes of GA aircraft, is high
enough to allow many fatalities per year across the fleet. If much
higher safety were achievable at a reasonable cost, the FAA would
presumably have set the probability threshold lower.

Second, for the more expensive classes of GA aircraft, that threshold
IS set lower, by two or three orders of magnitude! Presumably, that's
in part because the bigger planes can afford to meet higher safety
standards--standards that would swamp the cost of the smaller planes.

Third, those ACs set a CEILING for acceptable failure probabilities.
Unless I've missed something, there's nothing in the ACs to prevent
the FAA from deciding that a particular item of safety equipment is
required for airworthiness, even if the absence of that equipment
would still leave the catastrophe probabilities within the standards
set by the ACs. And cost is surely a factor in making THOSE decisions.
(For example, if ADS-B technology cost $500,000 per plane, the FAA
would not be proposing to require it.)


Your going to "fit right in" around here!



  #70  
Old February 25th 08, 08:34 PM posted to rec.aviation.piloting
Andrew Sarangan
external usenet poster
 
Posts: 382
Default Fuel Quantity Measurement

On Feb 24, 8:26 pm, "RST Engineering" wrote:
Because

a) floats inherently leak over time unless they are some light solid, and
then they have a tendency over decades to break down and saturate.

b) the "state of the art" for float sensors use a wiper against a nichrome
wirewound resistor and the wiper tends to wear a hole and the nichrome tends
to redistribute itself across the form somewhat nonlinearily.

c) just because it was good enough for Henry Ford, it's good enough for us
{;-)



Good point. I never thought about the leaking float.

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Time, running out of fuel and fuel gauges Dylan Smith Piloting 29 February 3rd 08 08:04 PM
Russian Airplane Instrument Gauges Steve Restoration 1 October 2nd 06 10:50 PM
Fuel Level Sight Gauges DonMorrisey Home Built 5 August 10th 06 05:00 AM
Need the temp and oil pressure gauges for a J3, where do I get them? Eduardo B. Restoration 0 December 5th 03 01:59 PM
FA: Vintage aircraft gauges Randal Peterson Aviation Marketplace 0 November 13th 03 03:05 AM


All times are GMT +1. The time now is 01:46 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AviationBanter.
The comments are property of their posters.