Burnelli CBY-3 Restoration Diary

June, 2019 update on the restoration of the Burnelli CBY-3 “Loadmaster” from restoration Crew Chief, Harry Newman.


Fuselage Exterior Painting

After a very cold and wet April, May and most of June we are excited to resume the exterior painting of the CBY-3.

The process for painting the exterior of the aircraft involves a number of sequential preparation steps for each of the three main colors employed - silver, red, and blue. These steps include completing all repairs to the aircraft's skin, applying the primer coat, wet sanding with a fine sandpaper, masking off the specific area to be painted, wiping the skin section with a cleaning/degreasing fluid and only then can the finish topcoat of paint be applied. This process is also very dependent on the weather conditions such as temperature and humidity.

Once the applied topcoat has been given time to cure, the process is repeated for the next area to be painted. Many hours of preparatory work takes place for every hour of actual painting.

A final coat of blue paint has now been applied to the nose of the aircraft. With the fabrication and installation of the port engine accessory cowlings we have now primed these areas and extended the area of blue over parts of the cowlings, consistent with photos from the CBY-3's history.

Preparations under way to extend the area of blue out to the port engine cowlings...
…and after the final blue finish has been applied to the upper cowlings. Once the paint has cured it will be masked off and the silver finish will be applied to the lower cowling section, seen here in white primer.
A top view of the port engine and cowlings before final painting…
…and after the application of the blue topcoat to the upper cowlings.

The upper portion of the cockpit has also received its final topcoat of gloss white paint.

The cockpit dome in its gloss white finish.

With the blue and white areas completed we can now mask them off to protect the finish and begin applying the predominant silver topcoat to the remainder of the fuselage. Since the CBY-3 is a large aircraft, this will be accomplished by sectioning off specific areas and painting each area in sequential order. We will begin with the all metal wing flaps and the fabric covered ailerons.

The flaps had been restored and primed several years ago and put into storage. We have now brought them back into the restoration hangar where we will begin the process of fine sanding and painting. We will also apply the silver finish coat to the remaining areas of the port engine and accessory cowlings, the entire bottom of the fuselage and to the lower sections of the twin boom tail assembly.

The previously restored wing flaps are next in the painting sequence. One more fine sanding and the flaps will be painted silver.

Propellers

The CBY-3 had a number of engine and propeller upgrades during its operational life. Our research reveals that the proper propeller blade designation for our engines was the Hamilton-Standard 6359A-18 Hydromatic. We are in the process of locating and acquiring six blades, which, along with the parts we have in our inventory will make up two sets of the three bladed propeller assemblies. We are fortunate to have several volunteers who had careers with Hamilton-Standard and they will take on the task of restoring and assembling the props.

This is one of two propeller hubs and domes currently being restored by volunteer John Smith who was an engineer with Hamilton-Standard before his retirement.
Here John is test fitting a "spider" assembly which connects the three propeller blades to the engine spline.

Cockpit and Instrumentation

The last remaining corrosion issues in the cockpit have been resolved and the interior is now being painted in preparation to install the cockpit instruments. Our research indicated that the CBY-3 had a Minneapolis-Honeywell C-1 Autopilot installed in the instrument panel, although it was missing from the aircraft when acquired by the museum. Armed with a photo of the autopilot we found a single example in the museum's parts inventory. With only minor repairs required, it has found a new home in the CBY-3.

The Minneapolis-Honeywell C-1 Autopilot about to be installed in the CBY-3 instrument panel.

Flight Control Surfaces

The restoration of the fabric covered control surfaces is nearing completion. The 35 foot long elevator is the last remaining element to be completed. New fabric has been applied and sealed with butyrate dope that stiffens and waterproofs the fabric. The fabric is then riveted in place. The elevator is made up of three sections and there are over 2500 rivets required to complete the application. (More details about this process are included in the September 2018 restoration update.) Tom Palshaw and his team have done incredible work on this highly specialized process.

Once the fabric has been applied it is heat treated to tighten the material around the structure of the control surface. This is done prior to riveting and doping.

Tom Palshaw uses a heat sensor to check the temperature of the iron he is using to heat treat the newly applied fabric on a section of the elevator.
Bob Clark (left) and Tom heat-shrinking the fabric prior to applying butyrate dope and rivets to the elevator.
Once the butyrate dope has cured it is time to paint. Here Steve Seiser applies a coat of white primer to one of the CBY-3's rudders.
After the primer has cured the final topcoat of red is applied completing the restoration of the control surfaces. Shown here are two rudders and an outboard elevator section.
One of the rudders as it appeared when removed from the CBY-3 at the start of the project…
…and after its completed restoration.

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