Rotary Aircraft Firewall Seal for Engine Servicing
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Solution Overview
Problem
In rotary aircraft, the existing firewall designs complicate the removal of engines for servicing due to their fixed nature, requiring partial disassembly and obstructing the removal of the driveshaft and reduction gearbox as a complete assembly.
Innovation Solution
A two-piece inlet plenum assembly with a removable upper portion for the firewall and inlet plenum wall, allowing the engine, driveshaft, and reduction gearbox to be removed as a single unit, facilitated by a flexible fireproof seal accommodating radial and axial engine movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed firewall design is used to provide fire protection, then fire barrier functionality is ensured, but engine removal and servicing becomes complicated requiring partial disassembly
Solution Approach 1:
The firewall is divided into two separate portions: a first portion that remains fixed to the airframe and provides the fire barrier, and a second portion that is removable to facilitate engine access. This segmentation allows the fire protection function to be maintained while enabling easy engine removal and servicing operations.
2Reliability
If a fixed firewall assembly is used to protect against fire, then fire safety is maintained, but the driveshaft and reduction gearbox cannot be removed as a complete assembly
Solution Approach 1:
The firewall assembly is segmented into a fixed first portion and a removable second portion. The removable second portion is specifically designed to clear the path for the driveshaft and reduction gearbox, allowing these components to be removed together as a complete assembly while the fixed first portion continues to provide fire safety protection.
3Ease of operation
If a removable firewall portion is added to facilitate engine access, then ease of servicing is improved, but device complexity increases
Solution Approach 1:
The removable second portion of the firewall is merged with the inlet plenum assembly, combining the fire protection structure with the air intake system. This integration allows the firewall to provide both fire barrier functionality and engine access facilitation without requiring a completely separate complex removable firewall mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables easier access, replacement, and servicing of the engine and drivetrain components by allowing the upper portions of the firewall and inlet plenum wall to be detached, reducing disassembly and reassembly time.
Implementation Method 1
The seal may be constructed of a flexible fireproof material
Data Source
Figure 1~2
Figure 3
Figure 4A
AI summary
One embodiment is an inlet plenum assembly for a rotary aircraft (101, 201) that includes an inlet plenum defined on a first side by an inlet plenum wall (312) and on a second side by a forward firewall assembly (308), the forward firewall assembly (308) having an inlet aperture (310) configured to receive a drive shaft (314) to rotatably couple to an engine (302); and a seal (320) connected to the forward firewall assembly (308) via a seal retainer (900) disposed around a periphery of the inlet aperture (310). The forward firewall assembly (308) may further include a forward firewall upper portion (402) and a forward firewall lower portion (404), the forward firewall upper portion (402) configured to removably seat to the forward firewall lower portion (404). The seal retainer (900) may be attached to the forward firewall assembly (402) via a plurality of bolts (902) disposed around the periphery of the seal retainer (900). In some embodiments, the seal (320) is connected to an inlet duct of the engine (302).