Author Topic: The H-250 (2500 series) Helio as of 01/19  (Read 169 times)

Doug Johnson 1

The H-250 (2500 series) Helio as of 01/19
« on: January 31, 2019, 09:38:10 AM »
I should have done this list before the H-295, it is actually before the H-295s in the build timeline.

The H-250 is the 4th production model of the Helios

                                                                                    H-250 2500 series
Of the 41 ''2500 series'' H-250 Helios, built 17 are still around 42.5 %, and of those 3 are projects 9 are located in the US, 3 in Canada, 1 in Oz, 1 in New Zealand, 1 in the Philippines, and possibly 1 in Mexico that I didn't count.

In ’63, A preproduction prototype a/c was built for the H-250 called the H-291. In ’64 it was the model H-250 preproduction prototype and later in ’65 after an engine change, the H-295 preproduction prototype. The "crash-cage/fuselage" was built as N9757 s/n 1. It was strengthened for about a 300 lb increase in useful load to 3400 gross weight and the cowling was slightly modified to accommodate a larger oil cooler and air induction inlet, and some other minor cosmetic changes were done. It was eventually converted to a U-10D/H-295 in ‘67.

The “H-250, 2500 series" is basically an economy version of an upgraded "H-395" with a 250hp non geared 0-540 Lyc using lower octane fuel. It was also strengthened for about a 300 lb increase in useful load to 3400 gross weight. The a/c is 6" longer forward of firewall due to lighter eng being moved forward using a dynafocal engine mount for CG weight and balance. The lengthened cowling was also slightly modified to accommodate a larger oil cooler and air induction inlet, and optional cowl mounted landing/taxi lts and beginning with c/n 2506, the lts in the cowl became standard equipment.

The Factory introduced this aircraft c/n 2501, N5444E built 05/64, as the Mark II H-250A Caballero Model and considered it the prototype, the first five H-250s were built without the landing lts in the cowling, factory flyers show an “A” suffix in the model designation H-250. ‘A’ was dropped without appearing anywhere but promotional info, testing continued on 2501 until 04/65, about the same time 2506 was built.

There is no STC for an upgross to the H-250, only 1 H-250s paperwork shows installation of the 120gal LR fuel bladders. 5 have been converted with the Go-480 to H-295 configuration but 1 one recently damaged beyond economical repair (not in this list) has had the model designation changed to H-295, it might have been eligible with the paperwork upgrade to a H-295 eligible to an upgross using a 1-time STC, type of field approval. 2 have been converted to 300 hp with the Fuel injected Lyc IO-54OK1G5 and Hartzell HC-C3YR-1RF 3 blade prop using STC, 2693NM. Another STC, SA1936CE for the 350 hp TIO-540 might be interesting as well. 1 H-391 c/n 047 in Brazil is believed to have been converted to H-250 configuration using Helio Factory mod #45 listed in registry as c/n 254.7

Below are the history paragraphs of the H-250, 2500s still in service.

« Last Edit: February 01, 2019, 02:07:38 PM by Doug Johnson 1 »