52478-1-ACP PMA Approved - Seal - Dome & Barrel (.025 Inch Oversize)

Tired of hydraulic fluid being slung from your prop across windscreens and engine cowlings?

Read our summary below on why we chose to produce these FAA-PMA approved Hamilton Standard propeller dome seals.

Our Motivation

Old embrittled, hardened & undersized rubber seals on warbirds just aren't cutting it anymore. The AirCorps Aviation engineering team and AirCorps Depot were able to apply for and gain FAA-PMA approval to produce a fresh new manufacture Hamilton Standard Hydromatic propeller dome seals. The value and rarity of propellers today puts pressure on shops, maintainers and operators to ensure prop longevity and proper maintenance.

Using the original Hamilton Standard drawings and engineering data was critical to the AirCorps FAA-PMA dome seal design where seal height and width dimensions is verified after seal is stretched and installed on a mandrel. As restorers, maintainers, suppliers and operators of these aircraft at AirCorps Aviation, we bring a first hand knowledge of these parts because we hear pilot feedback, we handle the parts and maintain the assemblies they are installed in. 

Where Used - Hydromatic Hamilton Standard Propeller Models: 23E50, 24D50, 33E60

• Hamilton Standard 23E50 Propellers: 
• 23E50-107, 23E50-109, 23E50-119, 23E50-137, 23E50-155, 23E50-163, 23E50-179, 23E50-181, 23E50-189, 23E50-231, 23E50-233, 23E50-241, 23E50-247, 23E50-285, 23E50-287, 23E50-301, 23E50-311, 23E50-315, 23E50-321, 23E50-327, 23E50-389, 23E50-391, 23E50-393, 23E50-399, 23E50-455, 23E50-471, 23E50-473, 23E50-473, 23E50-489, 23E50-491, 23E50-495, 23E50-505, 23E50-543, 23E50-591, 23E50-797
• Hamilton Standard 24D50 Propellers:
• 24D50-65, 24D50-71, 24D50-87
• Hamilton Standard 33E60 Propellers:
• 33E60-13, 33E60-15, 33E60-31, 33E60-33, 33E60-35, 33E60-79, 33E60-85
• Hamilton Standard Dome Assemblies:
• 59627, 59626, 54053, 55011, 55316, 54776, 55290, 57990, 55288, 59468, 59632, 61144, 59648

Background on Prop Dome Seal

When the propeller dome is installed on the hub assembly, the preload between the cam gear in the dome and the blade gears on the propellers is controlled by the distance from the bottom face of the dome to its mating surface on the hub. Maintainers can adjust this height, and therefore adjust preload, to account for wear by using thin donut shaped shims to space the dome from the hub assembly. The P-51 maintenance manual AN 01-60JE-2 page 181 provides great guidance on how to do this as well as other aircraft and Hamilton Standard maintenance manuals. The notes under figure 227 of AN 01-60JE-2 give guidance and reference to usage of the 52478-1 oversized dome seal. The oversized seal (52478-1) is used when the total width of preload shims under the dome assembly exceeds .025".

Do I need a Stock (52478) or Oversized (52478-1) seal?

Propellers were furnished by Hamilton Standard with both the 52478 (stock size) and 52478-1 (.025 oversized) seals to allow for usage of either during maintenance. While the propeller only requires one dome seal per propeller, we recommend that maintainers / operators stock both the stock 52478 and oversized 52478-1 seal sizes. Slight adjustments in the prop can require usage of a different seal.

This prop dome seal is commonly installed on these aircraft: 

P-51 MUSTANG - 24D50 - 6523 & 6547

B-17 FLYING FORTRESS - 23E50 - BLADE 6477

B-24 LIBERATOR - 23E50 - BLADE 6477

B-25 MITCHELL - 23E50 - BLADES 6477 & 6359A

C-47 SKYTRAIN, C-53 SKYTROOPER, DOUGLAS DC-3 - 23E50 - BLADE 6477

C-54 SKYMASTER - 23E50 - BLADE 6507

PBY CATALINA - 23E50 -BLADE 6353

F4U, AU-1, FG-1D CORSAIR - 23E50 - BLADE 6525

F6F HELLCAT - 23E50 - BLADE 6541

TBM AVENGER - 23E50 - BLADE 6359

LOCKHEED VENTURA - 23E50 - BLADE 6477

SBD DAUNTLESS - 23E50 - BLADE 6511

A-20 HAVOC / BOSTON - 23E50 - 6353

A-26 INVADER - 23E50 - BLADE 6359

C-82 PACKET - 33E60 - BLADE 6491

C-69 CONSTELLATION - 33E60 - BLADE 6491

Read about the development of this seal here:  click HERE