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Landing Gear Wiring Harness replacement kits.

  • Adjustment suggestion - down-lock limit switches. I would bet that this down-lock switch adjustment procedure is not well understood; a slight misadjusting here will allow the gear to be un-safe, i.e. not "down and locked" over center. I have encountered this misadjusted condition even on new harness installations; it can lead to a "gear collapse". I wish for all to be aware of this so shout it from the rooftops.


Who would be proud of this?

Reading from AC 43-13-1B, Chapter 9-7, section H as below

"Comanche Gear" landing gear wiring harness replacement kits are better than the factory-installed product. They are constructed of  properly marked MS22759 wire as in AC 43.13 chapter 11-88 where special considerations are to be given to Severe Wind And Moisture Problems [SWAMP wire]. If you're interested in reading more about this section 11, click the various links at the bottom of this page. These wire bundles are then covered with silicone-coated fiberglass sleeve and/or Teflon® tubing. All the wires are made to the correct length and terminated properly for easy installation, matching Piper's design. The kits are complete with all the nit-picking pieces that you would never believe are required, including a very detailed instructions manual with many color photographs illustration "how to". One challenge may be to get your A&P or installing agency to read and understand the instructions; for some reason us guys just don't like to read instructions. At a recent inspection seminar I looked at 12 Comanches, 3 had the new kit installed; and not even one was done correctly with respect to the cushioned clamps' orientation and harness routing. How difficult can it be to look at a color photograph and mimic what is depicted? If you can read and follow instructions, then you can install these kits correctly.

The good news? You do not have to remove the floor for access; no wiring is replaced inside the fuselage. The connection is done between the wing and the fuselage for the mains just like the original, and varies for the nose position. To access the main gear harnesses merely remove the aft-section of the lower wing root fairing to expose the connectors.

I am available to perform the landing gear wiring harness replacement on your Comanche at your location or in my hangar in Naples, Florida. For more information check the Migrant Worker link.

The differences between the 2 switch styles, rectangular and round.

rectangular switches, safety and down-limit
Round switches, safety and down-limit
Rectangular switch
Round switch - notice the defective MLG assist spring

Page one - of a typical installation manual; a photo in the rectangular-version manuals.

Photo - of the miscellaneous kit contents for a rectangular switch kit.

Photo - Amp crimper for butt splices used in the single Comanche landing gear wiring harnesses, nose gear harness. Plan ahead and request for this tool to be included with your harness kit purchase. If you are ordering an air shipment please note this tool adds 1 pound [15.5 ounces] and will add to your shipping cost. Obviously you pay the return shipping.

A few words about pricing of the landing gear wiring harnesses. The micro switches used in these kits are a single-source item, Honeywell being the only supplier. Semi-annually they raise prices and those dollar-amount price increases I pass along to you. When the new inventory reflecting that increase hits the parts room and my current inventory is depleted, the first kit shipped with those newly-priced switches will be priced accordingly.

Piper’s pricing has been escalating too, although most likely they factor a mark-up which will continually make their prices escalate faster for an identical switch purchased from me. The cost as of June 2010 for the 4 micro switches [no harnesses] from Piper for the twin is $1,787.34 . You be the judge.

The Landing gear wiring harness kit utilizing the rectangular-version micro switches are $665.00. Those models include all 180 / 250 / 400 / and twins through serial number 694.

Order by part number as follows:

single Comanche through serial number 2201 $771.00
single Comanche from serial number 2202 through 3687 $771.00
twin Comanche through serial number 694 $771.00
400 Comanche - all serials $771.00
Teflon® tubing
extra-cost option to all rectangular harness versions $189.00
Cadmium plated actuators; exchange only
$170.00 extra-cost option to all rectangular harness versions SHIPPED, which includes assembly onto your harness. This makes life easier for the installing agency. SHIPPED means I do not do the installation; the cadmium option is $100 if I install your harness kit because the $70 labor is already included in the cost of your installation. Clear as mud? I have a strict exchange rule for these switch actuators - 2 weeks for return of your actuators with no missing components, especially the bee-hive spring.




The above kits include a 39 [or 40 page] comb-bound installation instructions manual with many color photographs and references showing exactly how-to; no guessing. This subject isn't even discussed in the Comanche Service Manuals.

The Landing gear wiring harness kit utilizing the round version micro switches cost from $1,172.60 to $1,201.60. Those models include all 260 models, and the PA30 from serial number 695, and the PA39 all serial numbers.


single Comanche 260 all serial numbers $1,264.72
twin Comanche PA39 all serial numbers $1,264.72
twin Comanche through serial number 2000 $1,264.71
Teflon® tubing
extra-cost option to all round harness versions $189.00

Prices effective 12/2016; Honeywell will again raise prices in June.

The above kits include a 25-page comb-bound installation instructions manual with many color photographs and references showing exactly how-to; no guessing. This subject isn't even discussed in the Comanche Service Manuals.

The following are the round-version micro switches.

micro switch, nose gear down limit; 1CH21-4. Piper = Outrageous $CALL

micro switch, main gear down limit and safety [squat] on the left side of the twins; 1CH22-4. Piper = $Outrageous


micro switch, main gear down limit and safety; 1CH23-4.

Piper = $Outrageous



The following are the rectangular-version micro switch, and the switch mounting bracket.

487-820 ref
switch assembly, landing gear, aka 487-820, which is NLA from Piper as of 01/2008 @ $329.00 each. DT-2R-A7 is the micro switch component. $96.00

micro switch, nose gear and main gear down limit and safety; rectangular version. 487-820. Piper = $220.00 NLA. This is also the motor-arm / up-limit switch.

Actuator bracket, for the micro switch; part of Piper P/N 487-820, AKA "8AS28" Switch Asm. Honeywell's retail is $164.67 for the bracket. Limited availability. $106.00


Left main gear harnesses

These are the harness assemblies for the left main, round version on the left; each includes the down-limit and the safety [squat] micro switches.


This rectangular switch version is constructed using Teflon® tubing as an extra-cost option. The tubing is clear and adds support in the bend radii. more photos below.

If you want the fancy deluxe version with all the options - $1,130.00 EXCHANGE [return your old components that i supply cadmium plated].

And if you want to add the cannon plug option, see that page too.

assembled switch detail
marked wire visible through tubing


Nose switch detail

Teflon® and cadmium options; complete harness; $1,130.

Teflon® and cadmium options; nose switch detail


RH Teflon option
Teflon option right side detail

Teflon® option installation - right side

Teflon® option installation - right side


Here are some documents from AC 43.13 relative to the Electrical System

Chapter 11-88 in its entirety, 125 pages.

Excerpts: SWAMP wire; wiring replacement; splicing. MIL-W-22759/7 wire is quite a bit pricier than the typical Tefzel hook-up wire 22759/16; it is specified in AC 43.13 for wheel wells and wing folds. This is the wire I use for the limit switch harnesses.

Tables 11-11 & 11-12 - wire tables.

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