CALL FOR INFO: (406) 752-5092

1893 Airport Rd, Kalispell, MT 59901


  Apache to Diamond Geronimo












Whether you are an individual looking for a reliable, spacious business class aircraft or a flight school looking for an economical, sturdy multi-engine trainer, the versatile Piper Geronimo can meet all your needs.

Powered by Lycoming 180 HP engines, this six-seat aircraft has the ability to take off and land on shorter fields easily clearing 50 ft obstacles. A range of 1025 miles makes the Geronimo convenient for longer trips.

Tens of thousands of dollars were spent on engineering to obtain the optimum performance from the Apache airframe. Every change was meticulously designed and mated to the basic aircraft. Rigorous examination, with an abundance of in-flight testing, was completed on each innovation before submitting it to the FAA for approval. The thoroughness of the program is attested to by the complete lack of Airworthiness Directives recorded against the Geronimo during the 30 years it has been on the market.

The PA23 series has no history of spar breakage. The spar is actually a huge I-beam that runs thru the center of the wings and is joined in the center belly area. These aircraft are over-built and very rugged.

The fuselage is 4130 steel tube framed and also uses aluminum stringers and ribs for extra strength. The use of both aluminum & steel (dissimilar metals) required Piper to zinc-chromate the complete structure inside and out at the factory. For that reason it’s hard to find a PA-23 with any significant corrosion.

The weak spots have historically been in the tail, rudder/elevator areas. When we overhaul an Apache airframe, we completely strip the aircraft inside and out. All of the tail surfaces are removed including the vertical and horizontal stabilizers. We have STC SA2793SW which is a rudder bracket reinforcement, SA4007SW which is a structural improvement parts kit for the flaps and elevators. The whole aircraft is power-washed inside and out, all surfaces are inspected. The landing gear gets updated (much-stronger) drag links, the tail system attach areas get a doubler added and all new attachment hardware before the tail components are reinstalled. All hoses are replaced, control surface hinges/bearings…all hydraulic components overhauled, all moving parts in the whole airframe get re-bushed or bearings replaced as applicable….the list gets pretty long.

In short, we are very thorough with our airframe overhauls. Montana Diamond Aire has owned the STC’s that make up this conversion since 1996.

In addition to performance enhancing aerodynamic cowls, extended nose, windshield fairings, that fully enclose the main gears and flap gap seals, we offer a host of convenience mods such as third side windows and inflatable door seals. To see how the Piper Geronimo out-performs other multi-engine aircraft, please note the comparison charts below.






Standard Features Include:

  • Lycoming O-360 A1D 180 HP Engines
  • Hartzell HC-C2YK-2RB-7666A2 Props
  • Rams Horn Control Wheels
  • Tail Strobe
  • Dual EGT
  • Oil Warning Lights
  • Southwind 20,000 BTU Heater
  • Flap Gap Seals
  • One Piece SpeedSlope Windshield
  • Hoerner-Type Wing Tips






& Introducing the Next – Generation Piper Geronimo!

Powered by two factory-new Fuel Injected Lycoming IO-360 Roller Cam Equipped 200 HP Engines.

Montana Diamond Aire holds the exclusive STC for this engine upgrade for the Piper Geronimo.




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