When is a TSO required?

[bagarre]

It's probably been discussed in depth here before but, one can't search for a three letter word due to how the side is indexed.

So, on a Cessna 170, when is an instrument or device required to be TSO'd?
Some examples:

If I have the required engine oil pressure and temp gauges but want to install an engine monitor for additional information, does the engine monitor need to be TSO'd?

If I need to replace the cigar lighter (which is on it's own breaker now) does the outlet need to be TSD'd?

Installing an artificial horizon in a VFR vs IFR plane? Or an airspeed indicator for that matter (was the original TSO'd?)

Cheers

[T. C. Downey]

Nothing but the transponder and the ELT needs to be TSOed

[n2582d]

Tom,
I was taught to look for TSO C22 (x) on lap belts when doing annual inspections.

[T. C. Downey]

Tom,
I was taught to look for TSO C22 (x) on lap belts when doing annual inspections.

the OEM belts are TSO'ed, the new BAS shoulder harness says it is TSO'ed but has no tag.

I will check again today to see if my new set has a tag.

[n2582d]

I think shoulder harnesses fall under some other TSO. C114 perhaps? But as our aircraft did not require shoulder harnesses I don't think the FAA requires any TSO standard for retrofitted shoulder harnesses, figuring anything is better than nothing.

[Bruce Fenstermacher]

You may have TSO'd equipment installed but that does not mean the you are required to have TSO equipment installed. Our aircraft were certified before there was a single TSO which stands for Technical Standard Orders. Today much of the stuff we install meets a TSO since written.

So the only place one would need TSO equipment is those places such as the transponder, mode C and ELT where the regulation was righten covering your aircraft and specifying the equipment must meet a TSO.

The cigar lighter is a common part. Will not be a TSO to cover it. The original AH was an AN gyro and did not meet a TSO. Not sure if the airspeed indicator was also an AN unit. Tachometers in many old aircraft came directly from automobiles as well as the oil temp and pressure.

There is no specification for shoulder harness in our aircraft because they are not required. In fact you could use twine to make them so long as you don't modify any of the required systems or structure.

[BEEZERBOY]

FAR21.183 (yes, it applies to CAR certified aircraft)... lists 5 things that are officially aircraft parts. one of the 5 is OEM, so engine gauges installed by Cessna are good & probably do not have a TSO.... they do, however, have a Cessna part number. a required part must be replaced with the same, or an approved equivalent.

a TSO part is simply a part that is built to a known standard. flight instruments, compass, etc are all TSO. having a TSO does not necessarily make the part eligible for installation. TSO 62 for tires has 5 or 6 ratings. for instance, a TSO'd nose wheel tire for a Learjet is not suitable for installation on a Supercub. I had a customer that wanted to install a small non-TSO altimeter. I called my PMI at the FAA & he said no can do unless we test it to the TSO standard & it passes. then we could probably field approve it (this was back in the days of easy field approvals).

parts that have a PMA (parts manufacturer approval) are eligible, but may require additional approval (STC, field approval, FAA engineering, etc) for the actual installation. I think the Shaden fuel flow monitor is an example of that.

the other 2 things are.... standard hardware, meaning AN, MS, NAS and in some cases SAE..... and.... an "owner produced part". which give you mechanic the ability to duplicate a bent skin for instance (instead of buying a Cessna P/N). you can only make one, not 2 and sell the other. the "owner" part may still require further approval (21.305).

the long and short is, from the FAA point of view, every part you install has to be made under one of the 5, and may require additional approvals for the actual installation

[T. C. Downey]

Any requirements for part 91, are written into FAR 91.XXX

The BAS shoulder harness has a sticker on the reel that says the harness complies with TSO 91 C114.

I believe we have equipment that does not require TSO compliance in 91, but the equipment is also used part 135.

[T. C. Downey]

You may have TSO'd equipment installed but that does not mean the you are required to have TSO equipment installed.

WE do have performance rules in 43.18, but they are quite vague as to what the "Same as or equal to means"

[Bruce Fenstermacher]

WE do have performance rules in 43.18, but they are quite vague as to what the "Same as or equal to means"

It can be successfully argued that something that meets a TSO is not the same as something that didn't and not the "Same as or equal to", there for it should not be installed in place of the OEM. Remember it can not be "better than".

The fact that BAS harnesses meet a TSO is irrelevant. They have an STC to install their harness system in the aircraft they are installed in and there for it could be made to any standard they could get approved. This is not to say that meeting the TSO did not make getting the STC approval easier.

[GAHorn]

That's a nice, concise, summary Beezerboy.
But 21.183 is " Issue of standard airworthiness certificates for normal, utility, acrobatic, commuter, and transport category aircraft; manned free balloons; and special classes of aircraft." and does not address or require that all things installed in aircraft be identified as "aircraft parts".

An example might be interior equipment such as cabinetry, upholstery, and cigar lighters/accessory-outlets, many of which are automotive/household items and which may be installed upon inspection/field approval/minor-alteration rules.

Short answer to OP, "No." When our aircraft were certificated there were not "TSOs" and therefore none applied. Some regulatorily req'd equipment has been invented since then (ELTs, GPS's, solid-state radios, etc.) and some of those must meet installation/performance requirements defined by their TSO's....and so must meet those standards.
Most items in our aircraft are not req'd to be TSO'd, unless they are "essential" equipment such as req'd equipment (front seat shoulder harnesses installed in aircraft built after 1978(*) such as ELTs. VFR aircraft are not req'd to have TSO'd instrumentation as long as the instruments meet another form of FAA/CAA/Military approval (i.e., AN/NAS/MS).
In other words no matter how good they look, you may not install chineese copies of airspeed/altimetry in certified aircraft, (but you may install them in VFR-only ultralights and homebuilts.) AC 23-21 provides guidance for installing ordinary automotive replacement parts (such as V-belts for you guys operating belt-driven vacuum pumps), voltage regulators, generator/starter brushes, primary engine instrumentation, etc..

A cigar lighter is not req'd equipment, but it (and similar after-market items) must be installed IAW (in accordance with) applicable FARs/Advisory Circulars. (such as FAR 43.13(a)/(b). Paragraph (b) states: "Each person maintaining or altering, or performing preventive maintenance, shall do that work in such a manner and use materials of such a quality, that the condition of the aircraft, airframe, aircraft engine, propeller, or appliance worked on will be at least equal to its original or properly altered condition (with regard to aerodynamic function, structural strength, resistance to vibration and deterioration, and other qualities affecting airworthiness)."
The word "materials" applies to parts. One method to comply with that qualtity-requirement is to have mfr'r assurances such as TSO's, PMA's, or other standard such as AN/NAS etc.. However many parts such as found in our aircraft are automotive in origin. (I am thinking here of such items as mechanical fuel-quantity gauges, oil temperature gauges, vibrating-point voltage regulators, cigar-lighters....etc.)
We have a Member whose AP/IA insisted that his cigar lighter MUST be official "Cessna". He searched high and low and "lucked out" finding an N.O.S. one still in it's original, tattered, Cessna-envelope. (One can only imagine what Cessna might demand of such an item these days.)
As picky as I have been considered by many,.... I think that IA/AP stance is particularly assinine. It is similar to those who insist that light-bulbs/lamps must only be "GE", etc. (I wonder if any of those authoritarians have ever noticed that some lamps in the Cessna parts catalog were originally specified as "Mazda".)

The problem here is , ...you can lead a horse to water but you cannot make him drink. You can hand your IA/AP a cigar lighter...you may even hand him a ceramic-and-stainless steel one from a million-dollar yacht much better in quality than anything Cessna ever installed......but you cannot "make" your IA/AP installit unless he agrees it's applicable to aircraft use.
HE has to keep his certificates in order to earn a living and HIS FAA inspector has likely given him a personal opinion or two that he uses as a guide as to what he may/may not install in aircraft.

AS for an engine-monitor installed in addition to the other instrumentation already installed to meet requirements.....that is auxilliary equipment and must not interfere with the required equipment, but otherwise if it and the installation meets the quality standards for aircraft (FAR 43.13(b)....then it is legal to do so. IMO

[T. C. Downey]

I asked my FSDO rep this AM if seat belts were required to be TSO'ed, he says yes, it is in the production certificate for the aircraft. so yes they must be TSO'ed

[Bruce Fenstermacher]

I asked my FSDO rep this AM if seat belts were required to be TSO'ed, he says yes, it is in the production certificate for the aircraft. so yes they must be TSO'ed

Tom, I'm sorry your FSDO rep is wrong to make a blanket statement such as that. There where no TSOs when our aircraft where certified and so there where no TSOs for the original belts and there could not have been any TSOs as part of the original production certificate.

I could not find an AD or other directive requiring belts to be removed and replaced with belts meeting a TSO either. Perhaps he can point out the appropriate regulation if there is one. As for the shoulder harnesses he is absolutely wrong. Our 170s did not require shoulder harnesses for certification and they still are not required.

AC 21-34 spells out the steps one can take to install shoulder harnesses in aircraft that did not require them. Bottom line AC 21-34 says the system and materials do not have to meet any standard though it highly suggests they do. So one could use shoe strings for shoulder harnesses if they desire in our 170s.

[BEEZERBOY]

oop..... brain fart. 21.183 used to be the accepted definition for "airworthy" before it was put into FAR 1 a few years ago. (airworthy can be boiled down to 2 words.... conformity and condition).

what I meant to reference is 21.303, which also goes with 21.305 that I did reference. the FAA will hold that ANY part installed (as in permanently attached) must be approved under one of those 5 items.

flight instruments, seat belts, wheels, tires, brakes & more.... all TSO. I believe the were part of "Specifications" in the days before they were called TSO.... at least some items were for sure, but they did not have Type Certificates though. people don't reaslize it but the TC's go back to the 1926 Air Commerce Act.... it is the "recipe" for building an entire aircraft so that it conforms to type design. a TCDS (data sheet) is a very much shortened version of basic specs. that replaced the "Aircraft Specification" in the mid 1960s. The original Specifications had all approved equipment listed for a particular aircraft, the TCDS does not, an approved equipment list is also required to check conformity.

OEM made or installed parts are approved as part of a specific aircraft. interestingly enough.... almost all OEM parts catalogs are not considered approved data.... go figger

as for the seat belts..... 91.205
(13) An approved safety belt with an approved metal-to-metal latching device for each occupant 2 years of age or older

that was put into part 91 to do away with the old style fabric to metal belts. Part 91 covers any aircraft flying in the USA no matter where it was made or registered

[T. C. Downey]

I asked my FSDO rep this AM if seat belts were required to be TSO'ed, he says yes, it is in the production certificate for the aircraft. so yes they must be TSO'ed

Tom, I'm sorry your FSDO rep is wrong to make a blanket statement such as that. There where no TSOs when our aircraft where certified and so there where no TSOs for the original belts and there could not have been any TSOs as part of the original production certificate.

I could not find an AD or other directive requiring belts to be removed and replaced with belts meeting a TSO either. Perhaps he can point out the appropriate regulation if there is one. As for the shoulder harnesses he is absolutely wrong. Our 170s did not require shoulder harnesses for certification and they still are not required.

AC 21-34 spells out the steps one can take to install shoulder harnesses in aircraft that did not require them. Bottom line AC 21-34 says the system and materials do not have to meet any standard though it highly suggests they do. So one could use shoe strings for shoulder harnesses if they desire in our 170s.

When speaking to requirements, let's not consider any SB as requirements in part 91. The AC is also not a requirement, it is simply a method already approved by the FAA as acceptable data to make modifications.
and last, explain FAR 91.205(b) (13) An approved safety belt with an approved metal-to-metal latching device for each occupant 2 years of age or older.
explain how you would gain approval of a belt. = TSO, that's how.

the part number for the belts on the 170 production certificate was approved when the production certificate was approved as part of the aircraft design.. remember the quote in the airworthiness statement, and complies with its type design or its properly altered condition. placing shoulder harness in the 170 requires a 337 field approval, or an STC which by the way came with my BAS harness. That is a properly altered condition.