Safe Flight Speed Control

[skifire42]

Hi,

4489B has a lift indicator on both the left and right wings. The installation on the right wing does not look nearly as clean as the left wing installation (the standard stall warning switch), so we assumed that some day during our restoration we would have to figure out how to remove this piece and patch the wing.

Recently though, I noticed that 89B's packing list includes a "Safe Flight Speed Control System" accessory and I now think the second lift transducer is part of this system. I've found some old ads showing this accessory includes a round gauge that indicates between "slow" and "fast", so I guess it is basically an angle of attack indicator. I have also seen a couple posts on the forum that mention there would be some type of computer included in the plane.

Does anyone have any further info on this accessory? Or a longshot, does someone have these parts in their plane or on a shelf that we could look at to try and duplicate or buy?

Thanks!
-Ryan

[GAHorn]

Without photographs it's difficult to be certain what you are describing on your right wing, but what you describe on your left wing is likely a "lift detector" or "stall detector" made by Safe Flight of White Plains, N.Y. It was an option on earlier 170A models and mandatory (required) equipment on B models.

[n2582d]

AK172-11 is shown here. That would be cool if you could get that system up and running. As far as I could find it was never approved on the 170. What does your paperwork show? Do you have a field approval for its installation?

[n2582d]

It's interesting that this accessory is shown in the price list with other optional equipment for the 1956 C-170B but is not listed at all in the TCDS or in 1958 when AK172-11 lists it for the C-172 and in AK175-10 where the same kit is available for the 175, 180, and 182. It seems that by 1958 the 170 was a forgotten orphan. Being orphaned is not entirely a bad thing though as it seems some early C-172 AD's should also include the C-170 but don't.

[skifire42]

Thanks all for the info.

I found the attached ad on google that indicates this system may have been available as early as 1954. It also shows the instrument that I think I'm looking for. The wing transducer on the right wing looks very similar to the standard stall warning indicator on the left wing, but it looks like it is inserted from outside the wing and then riveted to the skin.

The "Safe Flight Speed Control System" is listed as a line item on both my original packing list and weight and balance/equipment list. It is not mentioned in the logs at all. One curious thing is that all of the other accessories on the packing list have an associated part number, while the speed control system is last on the list and does not have a part number.

-Ryan

[GAHorn]

It's interesting that this accessory is shown in the price list with other optional equipment for the 1956 C-170B but is not listed at all in the TCDS or in 1958 when AK172-11 lists it for the C-172 and in AK175-10 where the same kit is available for the 175, 180, and 182. It seems that by 1958 the 170 was a forgotten orphan. Being orphaned is not entirely a bad thing though as it seems some early C-172 AD's should also include the C-170 but don't.

It's been explained that a common misconception exists that items listed on the TCDS were approved for/by the TC holder (Cessna) for the aircraft via TC.. This is not always true. In the 1950's it was common for an aftermarket product mfr'r to obtain approval and the CAA would list the item as approved via addendum to the TC, usually indicated with an (*). A subsequent owner might obtain the various parts and, having installed them, be under the mistaken belief that the installation is now approved via TC..... Not true!
Similar to STC... the approval must be obtained from the product mfr/holder. An example of this is the Javelin baggage compartment fuel tank modification. Simply because the necessary various parts are obtained does not provide approval for installation because a "basis of approval" is not provided by the TCDS, but instead by the product TC/Holder.
Unless the aircraft has prior proof of basis of approval... Safe Flight (or heir) must provide the paperwork for approval (usually for fee.) (Check your aircraft logs for prior basis of approval and if you can find the gauge then it's a simple "repair".)

[Bruce Fenstermacher]

George, I completely disagree with your last statement.

If an item is on the TCDS whether approval was gained by the manufacturer or someone else, it is approved for installation. No further permission is necessary.

[lowNslow]

This is a tough one. Here is the paragraph from the TCDS, as usual per FAA it is rather vague so you could make an argument either way.


"Approval for the installation of all items of equipment listed herein has been obtained by the aircraft manufacturer except those items preceded by an asterisk (*). The asterisk denotes that approval has been obtained by someone other than the aircraft manufacturer. An item marked with an asterisk may not have been manufactured under a FAA monitored or approved quality control system, and therefore conformity must be determined if the item is not identified by a Form ACA-186, PMA, or other evidence of FAA production approval."

[Bruce Fenstermacher]

Karl, that paragraph does not say permission from the party that got approval from the CAA in most cases, is required.

How many Cessna 170 owners have permission from Scott for the 3200 installed on their aircraft?

[lowNslow]

You could also say the same for the Sensenich prop. That is why I said you could you could make the arguement either way.

[Bruce Fenstermacher]

You could also say the same for the Sensenich prop. That is why I said you could you could make the arguement either way.

Or said another way that paragraph is no help determining who's statement, mine or George's, is correct.

[GAHorn]

The Javelin heir, as well as the TactAir autopilot folks have been successful in their pursuit of claims (although they seem to prefer to avoid the legal expense of actual prosecution. Both of those products are owned by surviving family members of the original type design holder and are not large corporations with energetic legal departments.)

Scott became a Tyco company and delegated their interests to Cessna as a distributor of their product. (Their approval basis was as the OEM offering the item as original optional equipment. However they were not the OEM of the autopilots, nor the tandem gear, nor most of the other "asterisk" items, virtually all of which were installed after-market or by the delivering dealer without Cessna involvement.) It has since become a moot point because Tyco has abandoned the tailwheel business and ABW hasn't seemed to be bothered with such details on older aircraft. (They seem to have an issue with enforcement on installations preceding their product ownership. Besides, why PO the market-base for replacement parts?)

But that is an entirely different matter than ownership of a basis of approval. The TCDS is pretty clear that it's not Cessna, so I believe that would mean approval must come from a different source. I also believe that enforcement would likely come only as the result of an accident. For example, if my survivors attempted to sue TactAir because of an accident believed to have been caused by their autopilot, then TactAir would have a defense in that I had no basis of approval for the installation merely because CAA had indicated on a TC that the product had been found to be airworthy via separate approval, and that my acquisition of parts from a salvage yard provided no additional basis of approval.
I believe this is little different than buying Cleveland brakes from a salvage yard and installing the parts without either the appropriate STC or Field Approval. I also believe that unless I create the controversy or have an accident I'd likely get away with it. The problem might be that my back seat passenger's heirs might prevail against my estate.

[blueldr]

George,
If your estate was a turnip, like mine, no sane lawyer would be interested in taking the case. No blood at all, you know!

[GAHorn]

Karl, that paragraph does not say permission from the party that got approval from the CAA in most cases, is required.

...

Nor does STC paperwork. But we all know it is (required.) You must contact the supplemental type certificate holder to seek written permission.
Because it's listed on the TCDS does not grant permission for installation... it only means it does have a basis of approval.

[Bruce Fenstermacher]

Karl, that paragraph does not say permission from the party that got approval from the CAA in most cases, is required.

...

Nor does STC paperwork. But we all know it is (required.) You must contact the supplemental type certificate holder to seek written permission.
Because it's listed on the TCDS does not grant permission for installation... it only means it does have a basis of approval.

George, you are wrong. All STC paperwork now has the following statement. This is from one of our own Association STCs:

No written permission for an STC today, you can't use it. Items on the TCDS are not STC'd. They are approved items on the TCDS. That is why permission is not required.

I understand that STC paperwork did not always include this statement. I'm afraid many just copied paper and filled out a 337 and did not have permission required. Some STC owners have issued a blanket statement or letter giving anyone permission to use their STC on any aircraft that is on the eligibility list. STC's for dacron fabric covering and the glue and paint process for Poly Fiber and Ceconite, are two of these that come to mind. Today as I said all STCs have the statement and you must submit the permission that written permission when filling the 337. Before this paperwork went direct to Oak City, you wouldn't get it past most FSDO inspectors missing the permission.