Piper Apache Geronimo, Great Conversion

This Geronimo conversion was performed by Diamond Aire, current holder of the STCs.

By:     Norm Goyer

Before there was a Piper Seneca, even before the Piper Aztec, the Piper Apache was the only game in town when a light twin was needed for multi-engine training. Before we purchased our two Senecas, we would rent an Apache from owner Flavio at Flabob Airport to use as our multi-engine trainer. Our flight instructors called it the “Flying Sweet Potato,” but it worked. The Apache had an interesting history. In fact, it wasn’t even a Piper; it had been designed by Stinson. Originally, it had small 125-hp engines, two side windows and twin tails, ala the D-18 “Twin Beech”. Piper actually bought out Stinson to obtain this design. The Stinson 108 Station Wagon series came along with the package. Piper needed the twin to fill holes in their product line. In fact, there are still a few 108s flying with the “Piper” logo on the cowling. After discussing the Twin-Stinson with flight school operators and Piper engineers, it was determined that the aircraft needed to be simplified and made safer for single-engine flight. Piper responded by installing two outstanding Lycoming 150 hp engines and dumped the twin tails. They substituted a much larger single vertical stabilizer for added stability and better rudder effectiveness during single engine flight. Eventually, after the underpowered Apache received an update with larger engines, and a longer nose it was called the Aztec.

This Geronimo shows off the very pleasant lines of the remanufactured Apache by Diamond Aire.

One of our tie-down customers, an airline Captain, just happened to own an Apache. One day in the early 1970s, he flew it away for what he called an extensive overhaul. Many months later, we heard his familiar call sign on the Unicom and “4411Papa” had come home to roost. Except, nobody recognized it. It looked like a brand new aircraft and it literally was. You see, the Captain turned it over to Southwest Aero Mods that held all the STCs for what was called the Apache “Geronimo”. I always presumed that Geronimo was in fact “King of the Apaches”. If not true, it does make a good story. The Southwest Aero folks stripped the airframe down to the bare bones, restored every nut and bolt to either new or like-new condition. The auto guys call it a “frame-up restoration.”

The cockpit has also been modified with a more modern look and better placement of instruments.

I believe the last owner of the STCs is Diamond Aire of Kalispell, Montana. Diamond Aire’s John Talmage bought the rights in 1996. When they rebuild an Apache, in addition to larger engines and complete tear down, they install sleeker low-drag engine nacelles, an extended Comanche style nose, a raked faired windshield, wheel doors, which completely cover the retracted landing gear. The wing received new Hoerner-style wingtips, with or without extra fuel tanks, cargo doors, super soundproofing, including double-paned windows. I have flown both the stock Apache and the Captain’s 4411P Geronimo. What a difference! Everything wrong with the Apache was right with the Geronimo. It was a far safer airplane to fly. The single-engine performance was outstanding and it was easy to fly. The Geronimo flies faster, climbs better, is far more efficient and looks like a million bucks, but only costs about a third of that. The various firms who performed these STCs converted a large number of Apaches; some only had the engines updated, while others had all the STCs performed, such as on N411P. If you believe you would like a very nice inexpensive twin, search out a Geronimo converted Apache. This is an outstanding light twin aircraft.

It is hard to believe that this very tired looking Apache can be turned into a beautiful Geronimo.

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  1. John Talmage says:


    Thanks for mention in the above article.

    As well as owning all the STC’s that comprise the Piper Apache to Geronimo conversion, Diamond Aire owns most of the airframe modification STC’s for the Piper Aztec models. In addition we are currently installing our little-known 200 HP engine upgrade that allows the Piper Geronimo to be powered by 2 fuel injected Lycoming IO360-C1C engines. The aircraft in progress has 2 factory-new roller-cam equipped engines and we will be publishing test flight data on our weblog http://www.diamondaire.wordpress.com within the next few weeks.

    Diamond Aire is also in the process of having newly designed engine nacelles approved for the Piper Aztec aircraft.

    Thanks again,

    John Talmage

    Diamond Aire