What does "TSO'd" mean?
Eric Crump
I've been seeing this lately in aviation magazines. What is a TSO'd
headset, or GPS, etc? I can't find the definition on the internet.
Thanks -Eric
Sydney
Eric Crump wrote:
"TSO" stands for "Technical Standards Order".
I've never heard of a TSO'd headset, but basically the idea
is that the parts in question have met the FAA's technical
standards order for their intended purpose.
For example, a GPS which is advertised as "meeting TSO C129"
is being presented as meeting minimum standards to be certified as
an IFR non-precision and enroute GPS. IF the FAA has written
a TSO for headsets (????), a TSO'd headset is certified to
meet it. To the best of my knowledge, TSOs apply to equipment
permanently installed in the aircraft, but I could be wrong.
When does an item need to meet the relevant TSO and when
doesn't it matter is a much trickier question.
My answer, which the more knowledgable (RF, RN, etc) will
hopefully correct:
Now a days, parts installed in a certificated aircraft must
have some form of FAA blessing. But for an aircraft which is
not used for scheduled charter or carriage of passengers,
many parts (for example a radio) can be blessed according to
other FAA TLA. Other parts (for example the pitot-static
system, altimeter, transponder, encoding altimeter) must meet
the relevant TSO if the plane is used for IFR flight but not
otherwise. It gets very confusing very quickly, and one gets
different answers from different FSDOs (flight standards district
offices) working for the same FAA.
Some other TLA for other forms of FAA blessing:
ATC
aircraft type certificate, sometimes just 'TC'. Original
equipment w/ which aircraft was certified, or subtantially
equivalent where original not available
PMA
part manufacturing approval. FAA approval to sell parts for
installation either as substantially equivalent to original
equipment or as parts not required for airworthiness (radio)
Depending upon part, STC/TSO/or FMA may be required.
STC
supplemental type certificate. Non-original equipment determined
to be a suitable addition to or replacement for original equipment.
STC can apply either to a specific make and model of aircraft
(ie "STC for C172"), or to specific equipment (ie an engine)
installed in any appropriate make/model of aircraft (ie STC for
Lycoming O-360 series, OK for Piper 180/Archer, C177, AA5B etc)
337
Major Alteration and Repair form. Originally required by the
FAA only for major alterations or repairs such as replacing
the wings or installing vac. pump in venturi-equipped plane.
Now required for different things by different FSDOs. Typically
filed with the local FSDO upon installation of any equipment
not part of the ATC. Must be supported by manufacturer's data
indicating compliance with another TLA, or will require FMA
(field modification approval)
FMA
Field modification approval. What you need to install
equipment which is not STCd or TSOd and which is deemed by
the FAA to affect the airworthiness of your plane (eg vac
pump in venturi-equipped aircraft). Description of this
process by those who have undergone it is often unprintable.
MEH
Major Excedrin Headache. Physiological state acquired by
new plane owner struggling to understand the above
Hope this helps,
Sydney
jan-berend holzapfel
Very interesting!
> MEH
> Major Excedrin Headache. Physiological state acquired by
> new plane owner struggling to understand the above
and LOL as well,
Jan
Ron Natalie
Eric Crump wrote:
>
> I've been seeing this lately in aviation magazines. What is a TSO'd
> headset, or GPS, etc? I can't find the definition on the internet.
> Thanks -Eric
TSO means Technical Standards Order. That is, it's a standard
put out by the FAA. TSO'd presumably means compliant with the
TSO.
What TSO'd means to you depends on which TSO you are talking about.
With the exception of IFR GPS's and ELT's, by and large TSO's are
meaningless to Part 91 operators. However, any (major) alteration
to an aircraft must be in accordance with Type Certificate (i.e.,
how your plane was originally certificated), a Supplemental Type
Certificate (STC, an approved change to the original Type Certificate),
or by "data acceptible to the administrator." The last is extermely
nebulous. However, in some cases TSO's are considered to be the
acceptible data. Unfortunately, the FAA is remarkably inconsistant
on this interpretation from office to office and day to day.
-Ron
Rod Farlee
There are no TSO's for headsets or handhelds (GPS or nav/comm).
Just some minor notes...
Sydney <syd...@biochem.wustl.edu> writes:
> Other parts (for example the pitot-static
>system, altimeter, transponder, encoding altimeter) must meet
>the relevant TSO if the plane is used for IFR flight but not
>otherwise.
For FAR Part 91 operations, TSO is required only for the ELT (FAR 91.207),
transponder (91.215) and altitude encoder (91.217 and Appendices E and F).
VFR or IFR, makes no difference.
But as you say, an altimeter won't get a PMA unless it's TSO'd,
and you can't install it without a PMA unless it's original equipment.
>337 Major Alteration and Repair form. Originally required by the
> FAA only for major alterations or repairs such as replacing
> the wings or installing vac. pump in venturi-equipped plane.
Perhaps paradoxically, replacing a wing requires only a cryptic logbook
entry "Replaced p/n XX-XXXX per Service Manual para Y-YY".
Altering a wing, or repairing a spar, rib, control surface, semimonocoque
(stressed) wing skin, or replacing it's fabric requires a 337. See FAR 43
Appendix A for the definitions of major repairs and alterations. If it isn't
major, it's minor <grin>.
The vac pump installations I've seen require an STC. This is because
the aircraft Type Certificate explicitly required the venturi for IFR, so
removing it won't conform to the TC. Also some early Continental engine
models had no provisions for a vacuum pump in their Type Certificate, so
bolting on the pump and pulley won't conform either. Installing any STC
requires a 337 form be filed.
> To the best of my knowledge, TSOs apply to equipment
>permanently installed in the aircraft, but I could be wrong.
I think so; the only "portable" TSO'd items that I know of are life vests,
life rafts, and portable emergency lighting.
Apologies for wandering off-topic; these are things which pilots do not
need to worry about; A&Ps do, and owners might.
- Rod Farlee
Steve Peltz
In article <354DCB...@biochem.wustl.edu>,
Sydney <syd...@biochem.wustl.edu> wrote:
>STC
> supplemental type certificate. Non-original equipment determined
> to be a suitable addition to or replacement for original equipment.
> STC can apply either to a specific make and model of aircraft
> (ie "STC for C172"), or to specific equipment (ie an engine)
> installed in any appropriate make/model of aircraft (ie STC for
> Lycoming O-360 series, OK for Piper 180/Archer, C177, AA5B etc)
An STC can also mean operating the aircraft in a different way. For
example, using Mogas instead of Avgas is an STC, and often requires
NO equipment installation or changes. When you buy the STC, you get
a piece of paper saying you can now use Mogas.
Rich Ahrens
Rod Farlee wrote:
> There are no TSO's for headsets or handhelds (GPS or nav/comm).
Telex and Sporty's seem to disagree with you. In my latest Sporty's
catalog, the Telex Pro-Air 5000E headset is prominently labeled "TSO'd."
I've seen others also so labeled.
------------------------------------------------------------------------
|Rich Ahrens | Homepage: http://www.visi.com/~rma/ |
|r...@visi.com |-----------------------------------------------|
|"In a world full of people only some want to fly - isn't that crazy?" |
------------------------------------------------------------------------
Rod Farlee
pe...@jaka.ece.uiuc.edu (Steve Peltz) writes:
>An STC can also mean operating the aircraft in a different way. For
>example, using Mogas instead of Avgas is an STC, and often requires
>NO equipment installation or changes.
There is a consistant logic to this. The original Type Certificate specified
"Fuel: 80/87 octane avgas"or "91/96 octane avgas". To change fuel, the
TC must be amended with an STC. The FAA requires extensive flight
testing before the STC is issued, by the way.
(Note: many pre-1950 planes and engines were certified for "76 octane
gasoline" and can burn autogas without an STC.)
FAR 43 Appendix A (a)(2)(vi) says "conversion of any sort for the
purpose of using fuel of a rating or grade other than listed in the engine
specifications" is a Major Alteration. So it requires a 337 form, and the
STC is the FAA approved data for this.
FAR Part 21 describe TC and STC, Part 23 aircraft and Part 33 engine
certification standards, etc. The beauty of an STC is that it frees you,
the aircraft owner, from the unpredictable whims of your local FAA
inspector. An STC is FAA approved data, and your FSDO does not
need to approve it.
In contrast, there is no FAR that says an FAA inspector must act on a
337 field approval in a timely, consistant or predictable manner. Despite
hundreds of previous and identical 337 field approvals, he can hold yours
up for months or years, or arbitrarily deny it.
So an STC is a good thing!
- Rod Farlee
Rod Farlee
>STC
> supplemental type certificate. Non-original equipment determined
> to be a suitable addition to or replacement for original equipment.
> STC can apply either to a specific make and model of aircraft
> (ie "STC for C172"), or to specific equipment (ie an engine)
> installed in any appropriate make/model of aircraft (ie STC for
> Lycoming O-360 series, OK for Piper 180/Archer, C177, AA5B etc)
As a strange footnote to this whole mysterious process, did you know
that there are thousands of airplanes flying around with different engines
than they left the factory with, and no STCs?
There are PA-28-150 converted to PA-28-160, C-177 converted to
C-177A, AA5A converted to AA5B, etc under nothing more than a 337
form, sometimes (in earlier years) without any FAA field approval. That's
because each still conforms to its Type Certificate, which covered more
than one model (different engine in same airframe). Neither the engine
nor airframe were altered, the engine was simply removed (per the Service
Manual) and another engine installed (ditto), minor alterations made in
the exhaust and baffling, and a revised weight and balance computed.
It conforms to the Type Certificate, so doesn't necessarily need an STC.
In more recent years, an STC has become the norm because the engine
change affects the emissions and acoustics (see FAR 21.115 etc). This
means the FSDO cannot issue a field approval, and the regional ACO
(aircraft certification office) engineers must be willing to do so. An STC
avoids field approval problems, because it is FAA approved in advance.
Again, apologies for wandering far afield of the topic.
- Rod Farlee
highflyer
Rod Farlee wrote:
>
> pe...@jaka.ece.uiuc.edu (Steve Peltz) writes:
> >An STC can also mean operating the aircraft in a different way. For
> >example, using Mogas instead of Avgas is an STC, and often requires
> >NO equipment installation or changes.
>
> There is a consistant logic to this. The original Type Certificate specified
> "Fuel: 80/87 octane avgas"or "91/96 octane avgas". To change fuel, the
> TC must be amended with an STC. The FAA requires extensive flight
> testing before the STC is issued, by the way.
> (Note: many pre-1950 planes and engines were certified for "76 octane
> gasoline" and can burn autogas without an STC.)
>
certified to burn 80/87 Octane Aviation Fuel. These airplanes
were NOT certified to burn 100LL Aviation fuel. However, the FAA
required them to be fueled with 100LL without either an STC or any
testing. The result was a tremendous increase in full and partial
engine failures for many of these aircraft certified for 80/87 octane.
That was justified by the allegation that the certification was for
80/87 Octane or Higher Aviation Fuel.
> FAR 43 Appendix A (a)(2)(vi) says "conversion of any sort for the
> purpose of using fuel of a rating or grade other than listed in the engine
> specifications" is a Major Alteration. So it requires a 337 form, and the
> STC is the FAA approved data for this.
>
> FAR Part 21 describe TC and STC, Part 23 aircraft and Part 33 engine
> certification standards, etc. The beauty of an STC is that it frees you,
> the aircraft owner, from the unpredictable whims of your local FAA
> inspector. An STC is FAA approved data, and your FSDO does not
> need to approve it.
> In contrast, there is no FAR that says an FAA inspector must act on a
> 337 field approval in a timely, consistant or predictable manner. Despite
> hundreds of previous and identical 337 field approvals, he can hold yours
> up for months or years, or arbitrarily deny it.
> So an STC is a good thing!
> - Rod Farlee
An STC is unquestionably a GOOD thing. Unfortunately, they are also
expensive and difficult to obtain things. For example, there are NO
STC's for some aircraft for Mogas, even though they were designed and
certified for 80/87 Octane fuel because there are not enough aircraft
in the fleet to justify the cost of obtaining the STC.
Sydney D. Hoeltzli
Rich Ahrens wrote:
> Rod Farlee wrote:
> > There are no TSO's for headsets or handhelds (GPS or nav/comm).
> Telex and Sporty's seem to disagree with you. In my latest Sporty's
> catalog, the Telex Pro-Air 5000E headset is prominently labeled
> "TSO'd." I've seen others also so labeled.
Interesting.
While the FAA may have written a technical standards order for
headsets, in what context are headsets required to meet it?
Anyone know? Certainly not for use by GA pilots! Is there some
fine print somewhere requiring headsets worn by professional
pilots during Pt 135 or Pt 121 operations to meet a headset TSO?
To me, "TSO" wouldn't seem to have much meaning in that context,
unless someone happens to believe that a headset which meets an
FAA TSO is of higher quality than one which does not (dubious
belief, IMO, given the FAA's historical slowness to accept
technological innovation).
Sydney
a. m. boardman
Actually, there are, at least for headsets. When I got my DC10-13.4
repaired, it came back with a real live yellow tag complete with the TSO
it conformed with. Mind you, I've never discovered an operation that
actually requires a TSO'd headset, but perhaps they exist, and also
possibly only in other countries for which the US TSO is only a basis for
foreign certification...
andrew
Rich Ahrens
Sydney D. Hoeltzli wrote:
> While the FAA may have written a technical standards order for
> headsets, in what context are headsets required to meet it?
> Anyone know? Certainly not for use by GA pilots! Is there some
> fine print somewhere requiring headsets worn by professional
> pilots during Pt 135 or Pt 121 operations to meet a headset TSO?
Well, both Part 121 and Part 135 require two headsets (or one and a
speaker) for extended overwater or IFR operations, so I wouldn't be
surprised if there is a TSO setting the standards for them.
> To me, "TSO" wouldn't seem to have much meaning in that context,
> unless someone happens to believe that a headset which meets an
> FAA TSO is of higher quality than one which does not (dubious
> belief, IMO, given the FAA's historical slowness to accept
> technological innovation).
I haven't been able to find the TSO, but I could guess at some stuff
which might reasonably appear, like requiring ANR headsets to fail safe
or specifying an impedance so headsets can safely be moved between
aircraft with different audio systems.