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Scott OAT gauge

Jim Peace

By Jim Peace
in General Mooney Talk

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carusoam Grand Master

carusoam

Posted
Posted

JPI with an OAT probe mounted under the wing or mounted in an air intake near the cabin.

Digital display and aerodynamic.  Both are nicer when determining probability of ice while in IMC.

Best regards,

-a-

Andy95W Grand Master

Andy95W

Posted
Posted

I don't think the Scott thermometers were TSOed themselves.

TSOs and PMAs are pretty important for required equipment, but not so much for optional/nice to have equipment so long as it doesn't interfere with anything.  In a case like this it would be up to the installer to verify that it was not a required piece of equipment and that its installation was safe and appropriately completed.  Ask your A&P, or just have your hangar fairies replace it while you're not looking, IMO.

Andy95W Grand Master

Andy95W

Posted
Posted
7 hours ago, n74795 said:

Oat IS required for IFR flight 

Not that I've ever been taught, or taught any of my students.

Cut and pasted from FAR 91.205:

(d) Instrument flight rules. For IFR flight, the following instruments and equipment are required: 

(1) Instruments and equipment specified in paragraph (b) of this section, and, for night flight, instruments and equipment specified in paragraph (c) of this section. 

(2) Two-way radio communication and navigation equipment suitable for the route to be flown.

(3) Gyroscopic rate-of-turn indicator, except on the following aircraft: 

(i) Airplanes with a third attitude instrument system usable through flight attitudes of 360 degrees of pitch and roll and installed in accordance with the instrument requirements prescribed in §121.305(j) of this chapter; and 

(ii) Rotorcraft with a third attitude instrument system usable through flight attitudes of ±80 degrees of pitch and ±120 degrees of roll and installed in accordance with §29.1303(g) of this chapter. 

(4) Slip-skid indicator. 

(5) Sensitive altimeter adjustable for barometric pressure. 

(6) A clock displaying hours, minutes, and seconds with a sweep-second pointer or digital presentation. 

(7) Generator or alternator of adequate capacity. 

(8) Gyroscopic pitch and bank indicator (artificial horizon). 

(9) Gyroscopic direction indicator (directional gyro or equivalent).

 

The only other requirement for IFR equipment could come from the specific Type Certificate Data Sheet for the airplane.  The TCDS for the M20C does not mention an OAT.

  • Like 1
Andy95W Grand Master

Andy95W

Posted
Posted
7 hours ago, n74795 said:

 it needs to have a PMA , not a TSO...

Sorry, Alan, I also have to respectfully disagree with this, as well.  Typically, generic (not aircraft type specific) parts such as instruments are manufactured in accordance with an FAA established standard- the TSO.  PMA parts are specific to an aircraft type, such as a LASAR manufactured oversized nose gear bushing.

KSMooniac Grand Master

KSMooniac

Posted
Posted

If that was an original Mooney-installed part, then you can replace it with an identical part since the certification is covered by the approved type design, ie Mooney chose *that* thermometer and their engineering/drawings reflect the choice, which were then approved by the FAA.

I would take the opportunity to put something modern in there such as a Davtron unit if you have the room, or especially an engine monitor (which should already have!) that can add a probe.  Probes should be placed under the wing in an inspection panel (search up previous topics).

Andy95W Grand Master

Andy95W

Posted
Posted
32 minutes ago, n74795 said:
35 minutes ago, n74795 said:

So it is legal to fly in icing conditions without an OAT ??

I cannot remember ever seeing a requirement for it.

But I completely agree it wouldn't be prudent to fly IFR without one.

  • Like 1
DXB Grand Master

DXB

Posted
Posted

Before I had no functioning OAT.  Now I have independent JPI and Aspen probe numbers.  Pretty sure the day will come when I nervously wonder which is more accurate.

  • Like 1
Piloto Grand Master

Piloto

Posted
Posted

If you have a multiprobe EGT or engine analizer they would have provision for OAT. All that it takes is installing an external probe underneath the wing. It works pretty well and you do not need extra panel space.

José

Bob_Belville Grand Master

Bob_Belville

Posted
Posted
20 hours ago, DXB said:

Before I had no functioning OAT.  Now I have independent JPI and Aspen probe numbers.  Pretty sure the day will come when I nervously wonder which is more accurate.

I turned both on while the plane was parked in the hanger and compare all 3 readings (the 3rd being the original window mounted OAT). Either the JPI 930 or the Aspen has the capacity to enter a factor to offset the display. 

  • Like 1
N601RX Grand Master

N601RX

Posted
Posted

If you want to verify the accuracy you can use an ice bath.  An insulated cup filled with small ice chips and just enough water to cover them will give you a reference temperature very close to 32dF.  

If prepaired properly it can be a NIST standard.

Lood Mentor

Lood

Posted
Posted

Ridiculous, some of this certified BS.

Except for the price, I'll bet my last dollar that there's no real difference between a certified OAT gauge and a non-certified OAT gauge.

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