TURBINE FRAME ASSEMBLY - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General

Exploded View of Turbine Frame Assembly ** ON A/C NOT FOR ALL

The turbine frame module is the major structure assembly at the rear of the engine. It supports the low pressure turbine (LPT) rotor rear section and provides for engine rear mounting on the airframe.
The turbine frame consists of the following major parts :

Turbine frame.
No. 5 bearing support.

** ON A/C NOT FOR ALL

2. Description

A. Turbine Frame with Tangential Symetrical Section Struts

Post SB CFMI 72-0368

NOTE: This descripton is for Turbine Frame with Tangential Symetrical Section Struts only.

Turbine Frame Struts Section and Numbering ** ON A/C NOT FOR ALL

The turbine frame assembly is made of nickel alloy and consists of a hub and a polygonal outer casing connected with tangential struts of a symetrical section.

Exploded View of Turbine Frame Assembly ** ON A/C NOT FOR ALL

(1) There are 16 struts, airfoil-shaped and tangential to the hub. The struts provide internal passage for the following items :

Turbine Frame Section ** ON A/C NOT FOR ALL

(a) Aft sump oil scavenge tube (No. 7 strut)

(b) Oil supply tube for the No. 4 and No. 5 bearings (No. 10 strut).

(2) The aft sump overboard seal drain tube is routed between struts No. 7 and No. 8.

(3) The front flange of the outer casing is bolted to the LPT case. The outer casing rear flange supports the primary exhaust nozzle. At its periphery, there are 3 clevis mounts for engine/airframe adaptation, and 2 brackets for handling and installation on engine storage stand.

Turbine Frame Section ** ON A/C NOT FOR ALL

(4) On its front side, the hub of turbine frame has 2 attachment flanges that are, from the center and outward:

the hub inner front flange. This flange supports the No.5 bearing support.
the hub outer front flange. This flange supports the oil collector (aft oil sump assembly).

(5) On its rear side, the turbine frame has the following attachment items that are, from the center and outwards:

a flange located on the hub of turbine frame. This flange provides the support and attachment for the sheet metal flange assembly on its mid circle. This sheet metal flange assembly itself supports and centers the flame arrestor and also provides a rear support and centering for the oil inlet cover on its inner circle, and also supports and centers the flow path fairing on its outer circle.
a circle of studs (quantity: 16). There is a stud projecting rearward at the root section of each tangential strut. The studs provide support and attachment for the engine exhaust plug (centerbody) with nuts.

(6) The inner wall of the turbine frame gaspath is covered with the flow path fairing. The flow path fairing is a one part bolted to the plate lock, and to the flange assembly. This plate lock is mounted between the TRF, and the exhaust plug on the aft side.

B. No. 5 Bearing Support for Turbine Frame with Tangential Symetrical Section Struts

Oil Pressurizing Seals-Location ** ON A/C NOT FOR ALL

The No. 5 bearing support is made of steel alloy. Its outer flange is attached, with the oil collector (aft oil sump assembly), to the turbine frame with bolts. The inner front bore of the No. 5 bearing support accomodates the No. bearing outer race and an adjusting sleeve.
The rear face of the support carries the oil inlet cover which supports the oil supply tube for the No. 4 and 5 bearings, and provides for pressurization of the dual air/oil seal installed at the rear end of the center vent tube rear extension duct.
The oil inlet cover supports the rear extension duct. The No. 5 bearing support has machined passages for :

Pressurizing air to the oil inlet cover.
Sump bleed air to the center vent tube.
Oil to the scavenge tube.
Oil to the No.5 bearing "squeeze film" vibration damping system.

[Rev.10 from 2021] 2026.04.01 02:43:19 UTC