Safe Flight Lift Detector: A Guide, A Rant

[EricJ]

11 minutes ago, M20Doc said:

I’m confused, I thought that an A&P couldn’t replace a leaking compass diaphragm, how can one overhaul a lift detector/ stall vane.  There are no manuals covering this repair.

A compass is an "instrument", so has to go is supposed to go to a repair station qualified to repair that instrument.   It's a consequence of how that particular device is categorized.   A switch is not an instrument, nor are a lot of really complex things, like radios, various avionics boxes, etc., so all of those can be repaired by an A&P with the proper documentation.   An A&P can even open up a radio box and replace components on circuit boards, as long as they don't affect transmit signal characteristics, which requires a GROL (general radio operator's licence) from the FCC.

Or something like that. 

[Blue on Top]

On 5/6/2021 at 6:44 PM, M20Doc said:

And for those who don’t want to pay Safe Flight, Mooney had a replacement built in house.

OMG!!!  Wow!!!  This thread just got super freaky, crazy, mind-blowing for me!

The referenced part is a non-heated "switch", so cannot be used on FIKI airplanes.  The definition of "switch" here is really, really interesting.  I guess a magneto, a strobe, etc. are just "switches", too?  The position of that automatic switch shows compliance to an FAA (CAA) regulation.  I'm learning! 

PS.  The less expensive part is a grand (literally) improvement.

Edited May 10, 2021 by Blue on Top
Add the PS

[Minivation]

On 5/6/2021 at 7:44 PM, M20Doc said:

I’m confused, I thought that an A&P couldn’t replace a leaking compass diaphragm, how can one overhaul a lift detector/ stall vane.  There are no manuals covering this repair.

1. Important terminology difference between "overhaul" and "repair." The term "overhaul" refers to disassembly, cleaning, inspection, repair, reassembly, and testing, whereas "repair" can mean just about anything to bring back a certain component to working status. What was done here was a repair, specifically, a minor repair. In absence of a manufacturer-issued manual, AC43.13-1B Chapter 11 (and common sense) was used, under the same legal framework where a rusty nav light receptacle or leaky shimmy damper can be brought back to condition.

2. 14 CFR 65.81(a) specifies:

• A certificated mechanic may perform ... maintenance ... of an aircraft or appliance, or a part thereof, for which he is rated (but excluding major repairs to, and major alterations of, propellers, and any repair to, or alteration of, instruments)...

wherein "appliance" is defined in 14 CFR 1.1 as:

• Appliance means any instrument, mechanism, equipment, part, apparatus, appurtenance, or accessory, including communications equipment, that is used or intended to be used in operating or controlling an aircraft in flight, is installed in or attached to the aircraft, and is not part of an airframe, engine, or propeller.

and "instrument" is defined as:

• Instrument means a device using an internal mechanism to show visually or aurally the attitude, altitude, or operation of an aircraft or aircraft part. It includes electronic devices for automatically controlling an aircraft in flight.

Therefore, whereas a compass is:

1. an appliance
2. that uses an internal mechanism
3. to show visually the (lateral) attitude of an aircraft,

and is thus an instrument, a stall switch is:

1. an appliance
2. that uses an internal mechanism
3. but does NOT inherently show visually or aurally the attitude, altitude, or operation of an aircraft,

and thus, in my interpretation, is not an instrument and therefore falls into the scope of capabilities of an airframe-rated A&P as per 14 CFR 65.81. On the other hand, the compass should (I'm not saying it always is, but ... not my problem :)) be repaired by a 145 CRS with Class 1 Instrument rating or restricted rating explicitly allowing the make/model of that compass (e.g. Airpath, PAI-700, etc.).

On 5/6/2021 at 7:44 PM, M20Doc said:

And for those who don’t want to pay Safe Flight, Mooney had a replacement built in house.

That's good to know. Hopefully it doesn't cost an arm & a leg like the Safe Flight doorstop.

Edited May 12, 2021 by Minivation

[Andy95W]

Since the stall warning gives an aural alert of the attitude of the airplane, doesn’t that make it an instrument exactly in accordance with your reference?

[Minivation]

28 minutes ago, Andy95W said:

Since the stall warning gives an aural alert of the attitude of the airplane, doesn’t that make it an instrument exactly in accordance with your reference?

Key word is "inherently." The stall switch contributes to an aural alert but does not in of itself show (visually nor aurally) any indication whatsoever.

Edited May 12, 2021 by Minivation

[EricJ]

39 minutes ago, Andy95W said:

Since the stall warning gives an aural alert of the attitude of the airplane, doesn’t that make it an instrument exactly in accordance with your reference?

The actual aural alert in most airplanes comes from a sonalert, which does not seem to have ever been available from an FAA-PMA source.   Mallory even has a faq document on their website that says they've never been FAA-PMA.

https://www.mallory-sonalert.com/Documents/Faq/FAQ-Transducers-External Drive-Electromagnetic.pdf

Slightly off-topic, but I think interesting. 


 

[carusoam]

Key word seems to be... internally...

The stall sensor doesn’t have a visual or aural warning...

The aural warning (sonalert) doesn’t have an internal sensor... it has an external sensor...

Of course... going by the book can lead to misinterpretation...

Especially when read by a PP... 

 

If the stall warning doesn’t sound... I may not control the plane properly... when the plane is accidentally nearing a stall condition... while I’m blissfully unaware... 

So... the stall warning system that includes the sensor and the Sonalert... is used to control flight...  an important life saving portion of some flights... the sensor is internal to the system as a whole...

 

What is meant by an internal mechanism?

And why is that important?

Are we using it correctly?

Best regards,

-a-

[Andy95W]

20 minutes ago, Minivation said:

Key word is "inherently." The stall switch contributes to an aural alert but does not in of itself show (visually nor aurally) any indication whatsoever.

FWIW, I agree with your premise that an A&P can repair the switch.  I do not agree with your rationale and I think your reference material, in the hands of FAA inspectors, would lead them to the same conclusion as me.

[Minivation]

Just now, Andy95W said:

FWIW, I agree with your premise that an A&P can repair the switch.  I do not agree with your rationale and I think your reference material, in the hands of FAA inspectors, would lead them to the same conclusion as me.

You're entitled to your thoughts, and that's fine by me.

The FAR's can be very elaborate in some aspects, but also quite ambiguous in others. What constitutes the "basic design of the electrical system" in the context of major/minor alterations in 14 CFR 43 Appendix A? What does "other methods/techniques/practices acceptable to the Administrator" consist of in 14 CFR 43.13? ...... What exactly comprises an "instrument"? I firmly believe this is what A&P training is for. If the regulations specified every. single. policy, allowance, definition, exception, restriction, prohibition, etc. then the FARs would become too large to be practical and too complicated to maintain in the first place. In the absence the exact specifications from the FAA, it is ultimately the mechanic's responsibility to sometimes navigate these grey zones using sound judgment. And in the absence of specific guidance for a very particular task, things ultimately depend on the closest applicable data (AC43.13 in this case) and the mechanic's sound judgment on how to carry out that task all the while evaluating the potential consequences of various failure modes of that procedure and weighing the risks therein (and that's part of what A&P training is for).
 

1 hour ago, EricJ said:

The actual aural alert in most airplanes comes from a sonalert, which does not seem to have ever been available from an FAA-PMA source.   Mallory even has a faq document on their website that says they've never been FAA-PMA.

The exact Sonalert is Mallory P/N SC628, and correct - the part in of itself does not have any particular FAA "blessing" bestowed upon it. However, when Mooney procures that part from Mallory, passes it through its QC program, and designates it a Mooney part, then it becomes part of the M20's certificated type design, and through that association with the M20, itself becomes a "certified" part.

[Guest]

2 hours ago, Minivation said:

1. Important terminology difference between "overhaul" and "repair." The term "overhaul" refers to disassembly, cleaning, inspection, repair, reassembly, and testing, whereas "repair" can mean just about anything to bring back a certain component to working status. What was done here was a repair, specifically, a minor repair. In absence of a manufacturer-issued manual, AC43.13-1B Chapter 11 (and common sense) was used, under the same legal framework where a rusty nav light receptacle or leaky shimmy damper can be brought back to condition.

2. 14 CFR 65.81(a) specifies:

• A certificated mechanic may perform ... maintenance ... of an aircraft or appliance, or a part thereof, for which he is rated (but excluding major repairs to, and major alterations of, propellers, and any repair to, or alteration of, instruments)...

wherein "appliance" is defined in 14 CFR 1.1 as:

• Appliance means any instrument, mechanism, equipment, part, apparatus, appurtenance, or accessory, including communications equipment, that is used or intended to be used in operating or controlling an aircraft in flight, is installed in or attached to the aircraft, and is not part of an airframe, engine, or propeller.

and "instrument" is defined as:

• Instrument means a device using an internal mechanism to show visually or aurally the attitude, altitude, or operation of an aircraft or aircraft part. It includes electronic devices for automatically controlling an aircraft in flight.

Therefore, whereas a compass is:

1. an appliance
2. that uses an internal mechanism
3. to show visually the (lateral) attitude of an aircraft,

and is thus an instrument, a stall switch is:

1. an appliance
2. that uses an internal mechanism
3. but does NOT inherently show visually or aurally the attitude, altitude, or operation of an aircraft,

and thus, in my interpretation, is not an instrument and therefore falls into the scope of capabilities of an airframe-rated A&P as per 14 CFR 65.81. On the other hand, the compass should (I'm not saying it always is, but ... not my problem :)) be repaired by a 145 CRS with Class 1 Instrument rating or restricted rating explicitly allowing the make/model of that compass (e.g. Airpath, PAI-700, etc.).

That's good to know. Hopefully it doesn't cost an arm & a leg like the Safe Flight doorstop.

The point that I’m trying to make (apparently not clearly) is that there is no manual that I’ve seen from Safe Flight for repair of their lift detector/ stall switch, yet I do have a manual covering Airpath compasses.

 It’s fine to say that it’s within the scope of an A&P licence to repair it, but where’s the manual or approved data to tell him how to do it?  

Clarence

[Andy95W]

15 minutes ago, Minivation said:

 I firmly believe this is what A&P training is for. If the regulations specified every. single. policy, allowance, definition, exception, restriction, prohibition, etc. then the FARs would become too large to be practical and too complicated to maintain in the first place. In the absence the exact specifications from the FAA, it is ultimately the mechanic's responsibility to sometimes navigate these grey zones using sound judgment. And in the absence of specific guidance for a very particular task, things ultimately depend on the closest applicable data (AC43.13 in this case) and the mechanic's sound judgment on how to carry out that task all the while evaluating the potential consequences of various failure modes of that procedure and weighing the risks therein (and that's part of what A&P training is for).
 

I got my A&P in 1998, IA in 2003, and worked at the Williamsburg airport (KJGG) as such 20 years ago.  We probably know some of the same people.

That’s why I still think your interpretation of the regs you posted would be different from a Fed’s.

Edited May 12, 2021 by Andy95W

[Minivation]

48 minutes ago, Andy95W said:

I got my A&P in 1998, IA in 2003, and worked at the Williamsburg airport (KJGG) as such 20 years ago.  We probably know some of the same people.

That’s why I still think your interpretation of the regs you posted would be different from a Fed’s.

Wow, cool! JGG is just up across the bay from where I fly out of. Lovely airport.

While I don't have nearly the years under my belt as you do, I worked most of my career so far in Charlotte, where I know the inspectors there are more allowing of these matters (or at least so when I was there ... this actually isn't the first time this particular type of work was done). That said, I do know different FSDO's have different temperaments, so I wouldn't be surprised if the local guys have a different take.

[EricJ]

49 minutes ago, Minivation said:

The exact Sonalert is Mallory P/N SC628, and correct - the part in of itself does not have any particular FAA "blessing" bestowed upon it. However, when Mooney procures that part from Mallory, passes it through its QC program, and designates it a Mooney part, then it becomes part of the M20's certificated type design, and through that association with the M20, itself becomes a "certified" part.

I agree.   There are a bunch of parts that fall under this category, including the sonalerts, gear relays (timely in a different thread), microswitches, cabin speakers, etc., etc.   There are a number of ACs that provide guidance in how to deal with such things in reasonable and practical ways.   Many, however, seem to think only the narrowest interpretations of select regs are applicable.

38 minutes ago, M20Doc said:

The point that I’m trying to make (apparently not clearly) is that there is no manual that I’ve seen from Safe Flight for repair of their lift detector/ stall switch, yet I do have a manual covering Airpath compasses.

 It’s fine to say that it’s within the scope of an A&P licence to repair it, but where’s the manual or approved data to tell him how to do it?  

The front page of AC 43.13 essentially says that in the absence of other approved data the accepted data in AC 43.13 can be used as approved data.   That covers an awful lot of ground.

The Coleal letter and things like AC 43-12A Chg1 demonstrate that the narrow, strict interpretations of rules in the face of practicality often aren't.

[Blue on Top]

This is all extremely interesting, and I am not taking sides either way, but I am curious ...

I have looked at many, many Safe Flight "Lift Detectors" (switches) and have not noticed the normally required TSO markings.  In this case, TSO-C54, "Stall Warning Instruments."  This is true for Safe Flight units, Mallory Sonalert (SC628) (and other similar horns) or Cessna reeds (kazoos).  What validates that the device can withstand the environmental conditions that it is subjected?  And, along those lines, that a repaired unit continues to meet those requirements.

Another wrench in the gears is that the switch (and horn) is required to meet a certification regulation, "stall warning".

Thanks!  All y'all are awesome!
 

[EricJ]

2 hours ago, Blue on Top said:

This is all extremely interesting, and I am not taking sides either way, but I am curious ...

I have looked at many, many Safe Flight "Lift Detectors" (switches) and have not noticed the normally required TSO markings.  In this case, TSO-C54, "Stall Warning Instruments."  This is true for Safe Flight units, Mallory Sonalert (SC628) (and other similar horns) or Cessna reeds (kazoos).  What validates that the device can withstand the environmental conditions that it is subjected?  And, along those lines, that a repaired unit continues to meet those requirements.

Another wrench in the gears is that the switch (and horn) is required to meet a certification regulation, "stall warning".

Thanks!  All y'all are awesome!
 

What is a "Stall Warning Instrument"?  It isn't defined in the TSO, and the SAE document is not publicly available that I can find.   Whatever it is, I've never seen anything in a GA airplane compliant with B.2.v which says there must be a positive indication, readily discernible under any lighting, that the "stall warning instrument" has lost power.   There's also nothing in the Mooney SMM that says any of the components have to meet TSO-C54.   I can't find any reference in the SMM or IPC for my M20J of any TSO at all for anything.   

[N201MKTurbo]

Like the FAA man told me, and I’m paraphrasing, if you fix it and it works as intended, nobody cares. If you fix it and it causes a problem, and you cannot justify your repair method, then there is a problem.

[EricJ]

13 minutes ago, N201MKTurbo said:

Like the FAA man told me, and I’m paraphrasing, if you fix it and it works as intended, nobody cares. If you fix it and it causes a problem, and you cannot justify your repair method, then there is a problem.

I think the exact words (or very close) when we were at the IA seminar were:, "It's not a problem if it's not a problem.   If it's a problem, then it's a problem."    At the time it made total sense to me.   Still does. 
 

[N201MKTurbo]

3 hours ago, EricJ said:

I think the exact words (or very close) when we were at the IA seminar were:, "It's not a problem if it's not a problem.   If it's a problem, then it's a problem."    At the time it made total sense to me.   Still does. 
 

That was the exact quote, you were standing right next to me.

[Will.iam]

4 hours ago, EricJ said:

I think the exact words (or very close) when we were at the IA seminar were:, "It's not a problem if it's not a problem.   If it's a problem, then it's a problem."    At the time it made total sense to me.   Still does. 
 

Well if that was the only governing statement then duel electronic ignition should fly right through that process, right?

[N201MKTurbo]

9 minutes ago, Will.iam said:

Well if that was the only governing statement then duel electronic ignition should fly right through that process, right?

That would be a problem.

[Will.iam]

36 minutes ago, N201MKTurbo said:

That would be a problem.

Only when the engine quit. No problem no problem. JK i know we can’t put a second electric ignition even though in the experimental world they do it all the time.  

[toto]

14 minutes ago, Will.iam said:

JK i know we can’t put a second electric ignition even though in the experimental world they do it all the time.  

All you have to do is swap out the unpopular "separate mags" accessory case for a single D3000 mag, and then you can get a dual electronic ignition from Electroair today 

[Will.iam]

7 minutes ago, toto said:

All you have to do is swap out the unpopular "separate mags" accessory case for a single D3000 mag, and then you can get a dual electronic ignition from Electroair today 

Not an option for the 252. 

[toto]

7 minutes ago, Will.iam said:

Not an option for the 252. 

Yeah, I had a saw you were a K driver and went, well, crap, there goes my one chance ever on MS to brag about having a dual mag

(But then I did it anyway..)

[N201MKTurbo]

1 hour ago, Will.iam said:

Only when the engine quit. No problem no problem. JK i know we can’t put a second electric ignition even though in the experimental world they do it all the time.  

It’s OK, I won’t rat you out. 
 

But don’t bring it to me for an annual.