Frequently Asked Questions: Purchase and Installation

How can I get in touch with InAir Instruments, LLC?

For further information or to place an order please call or e-mail:

(614) 890-6301

What is the current price list for the LRI?


$ 450.00 without heat

$ 550.00 with heat

Shipping and handling USA, express carrier service, insurance add: $35.00.

Shipping and handling international, express carrier service, insurance add: $50.00.

Ohio residents add 6.5% for state sales tax.


Methods of payment:


We accept Visa, Master Card and American Express.

Check or Money Order made out to InAir Instruments, LLC

International payments can be wired directly to our bank. Please e-mail for instructions.

To Order:

Call order to: (614) 890-6301


Mail order to: InAir Instruments, LLC;

7188 Hollandia Drive; Westerville, Ohio; 43081-9319


What is included in each kit?

Each Lift Reserve Indicator kit includes the following:

What is the approximate installation time?

Typical installations take between 4 - 12 hours of shop time.

How much does the installed Lift Reserve Indicator weigh?

Less than two pounds.

What paper work is required by the FAA?

The Lift Reserve Indicator simply requires a form 337 to be filed.

Does the installation time include calibration?

Generally, yes.

What is involved in the calibration?

The time to calibrate typically is an hour which includes three adjustments to establish the correct angle of the probe.


The entire calibration procedure consists of adjusting the angle of the probe so that the indicator's needle reads one division below (to the left of) "zero" at the instant of flared touch down with application of full up-elevator control. Variations in flap setting, center of gravity, and wing loading have no bearing on the reproducibility of this calibration.

Fly the aircraft around the pattern and land as slowly as prudent by reference to the conventional instruments. At the moment of flared touchdown, with full up-elevator control applied, observe the LRI reading. If the reading is one division below (to the left of) "zero", no further calibration is needed. The LRI is calibrated to indicate zero lift reserve when dynamic lift is at the threshold of supporting the aircraft (one g of lift), elevator authority is lost, and mushing sink is imminent.

If the LRI needle reads below (to the left of) the indication which is one division below (again, to the left of) "zero" remove the probe and, rotate the probe rearward (steepening the angle) approximately one degree for each division that the needle deviated from one division below 'zero". Rotate the probe forward (lessening the angle) if the needle was above (to the right of) one division below "zero".

When the LRI is properly calibrated, make a slight scratch along the side of the probe where it meets the mounting bracket. This reference scratch should be checked as part of your pre-flight visual.

Can the instrument be panel mounted instead of glare shield mounted?

Yes. Many pilots prefer the LRI on the glareshield for ready reference when scanning the horizon.

Does the Lift Reserve Indicator come with a guarantee?

The Lift Reserve Indicator comes with a lifetime guarantee to the original purchaser on the original installation. All that is necessary is to include in you order the N number of the aircraft and the name of the registered owner of the aircraft on which the LRI is to be installed.

Can any A / P mechanic install the LRI?

Yes. The Lift Reserve Indicator is relatively simple to install. Any qualified A and P mechanic will be able to accomplish this.

Are there any LRI pilots in my area that I can talk to about the LRI?

Yes, quite probably. Please e-mail us and we will see if there is an LRI flying in your area.

I am interested in the Lift Reserve Indicator for agricultural aircraft. I fly a Grumman Ag-Cat. Will the device work on a bi-plane?


One of the main features of the LRI is its ability to compensate for weight change during flight. It doesn't care what you weigh. The LRI will always give you the stall protection required. The LRI will always show you the amount of available lift at the present time. So for the big turn at the end of the field or the heavy takeoff or landing on the short fields, you will always be aware of what you can do and not do. You will be flying slower and landing shorter than you thought you could and still maintain safe controllable flight.

On a bi-plane the probe must be mounted on the forward wing since that is the wing that will stall first.

Thank you for your interest.


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