20230112 153623
This is the oil cooler air intake cowl prior to bead blasting. The front of the cowl sits at the lower edge of this picture.Note the dents in the intake door which will need planishing out. Each of the Dzus fasteners needs replacing as well. (photo via Pioneer Aero Ltd.)

Oil Cooler Air Intake:

The oil cooler air intake cowling and its associated door form the bottom section of the accessory bay cowling assembly. The example which came with the project was in good overall condition but required repairs and a good cleanup before it could return to service.

20230112 153632

Another view of the oil cooler intake cowl prior to media blasting, this time from the opposite side. The door pivots on bolts 3/4 of the way up the cowl. It is actuated via a cable attached to the bar visible on the door at the lower edge of this picture. The movable flap on the inside of the door fits into the oil cooler intake duct to ensure a smooth flow of air. (photo via Pioneer Aero Ltd.)

20230308 155348

This is the oil cooler intake cowl (sans door) after bead blasting. The only repairs it required involved shooting replacement rivets through a handful of failed spot welds. (photo via Pioneer Aero Ltd.)

Intake Door Repairs:

The door is based around a tubular structure with skins welded onto it. While the sheet metal was in good overall condition, with only minor dents to planish out, the bar to which the actuating cable attaches was a different story. It was both bent and cracked. Pioneer Aero's engineers had to cut out the damaged sections of tubing and weld in replacement material. (photo via Pioneer Aero Ltd.)

20230313 092126

An edge-on view of the oil cooler intake door following bead blasting. (photo via Pioneer Aero Ltd.)

20230313 092048

A closeup of the intake door. Note the cracked piece of tubing and how it is bent about 45 degrees out of position. (photo via Pioneer Aero Ltd.)

20230314 130721

A view of the oil cooler intake door with the actuating bar detached for repairs. The damaged areas of tubing have been removed. This image shows the replacement sections; one in place, with the second being ready for positioning. (photo via Pioneer Aero Ltd.)

20230314 141241

Once the replacement sections of tube had been welded in place on the oil cooler door, the actuating bar was itself welded back onto the structure. The weld beads, seen in this image, were later filed smooth to match the part’s original profile. (photo via Pioneer Aero Ltd.)

20230308 154655
This mixture of oil and dirt, perhaps dating from WWII, was flushed out from inside the oil cooler intake door. As already noted, the door comprises a tubular structure with skins welded onto it, which meant that the inner and outer door skins could not be separated without incurring major damage to the part. Consequently, the only way to remove this oily muck was to scrape and flushed out through a tiny 1" gap! (photo via Pioneer Aero Ltd.)

Moveable Flap Repairs:

As images above reveal, the oil cooler air intake door features an inner flap which helps direct and smooth out the air flow as it enters the ductwork. Due to years of use, the aft edge of this flap had worn away in places. Thankfully, rather than discarding the part and fabricating an entirely new replacement, Pioneer's magicians were able to execute repairs to save most of this original component.

20230308 155411

This is the movable flap which attaches to the oil cooler intake door. The aft edge (visible at the top of the image) has signs of wear from rubbing against a stainless steel strip in the oil cooler intake duct. Pioneer effected repairs by replacing the flap edge with new material.(photo via Pioneer Aero Ltd.)

20230310 160414

A view of the movable flap for the oil cooler intake door showing the pre-drilled aft-edge replacement section prior to its being riveted in place. This new material was joggled and shaped to ensure that its edge sits in exactly the same position as the original. (photo via Pioneer Aero Ltd.)

The finished part:

After effecting repairs, Pioneer Aero applied a coat of primer paint to the oil cooler air intake cowling components. They temporarily assembled the parts for trial installation in the accessory bay cowling to ensure everything fitted correctly.

20230324 160922

The oil cooler intake cowl assembly following the completion of all repairs is seen here, temporarily fitted together, following a coating of primer paint. (photo via Pioneer Aero Ltd.)

20230324 160930

Another view of the oil cooler air intake cowl assembly following the completion of its repairs. The door is shown in the closed position. (photo via Pioneer Aero Ltd.)

Trial Fitting:

After completing repairs to the oil cooler air intake cowl, Pioneer Aero's engineers were finally able to trial fit the entire accessory bay cowling assembly.

20230421 110137
The oil cooler air intake cowl section, its door open, is seen here nestled within the entire accessory bay cowling and diaphragm assembly on the old MGM wind machine. (photo via Pioneer Aero Ltd.)
20230421 110046

The right side view of the engine accessory bay cowling assembly. Note the oil cooler air intake door is open at the bottom of the image. (photo via Pioneer Aero Ltd.)

20230421 105959

This image shows the lefthand side of the fully-installed engine accessory bay cowling assembly, along with the diaphragm on the old MGM wind machine. (photo via Pioneer Aero Ltd.)

20230421 110129

Another view of the top accessory cowl and diaphragm trial-fitted to the MGM wind machine. The rectangle, bare aluminum opening above the engine serves as the carburetor air intake box. The two circular ports either side of this fitting are the openings through which the machine gun barrels will appear. (photo via Pioneer Aero Ltd.)

20230421 111813

A view of the top cowl. Note the unpainted righthand gun trough. It still needs repairs but will be the next item Pioneer works on. (photo via Pioneer Aero Ltd.)