Overview
The air intake is a cowl that lets air into the engine fan inlet without change to the flow. The air intake is the same for the left engine and the right engine.
The air intake is an interchangeable assembly that gives a linear flow of air into the engine. It is installed on the forward flange of the engine fan.
The Thermal Anti-Ice (TAI) system is attached to the piccolo tube at the aft bulkhead of the nacelle inlet.
Inlet
The inlet has a nose lip which is a one-piece corrosion resistant steel attached to a titanium forward bulkhead. Its leading edge has a smooth, shiny aerodynamic surface. The nose lip is the forward wall of the TAI compartment.
The forward bulkhead is a 0.050 in thick titanium which gives support for the nose lip, and it is the aft wall of the TAI compartment. The forward bulkhead has a top half and a bottom half which are mechanically attached with splices.
The aft bulkhead attaches to the forward bulkhead by the inner and outer barrels. It is made from graphite/expoxy/Nomex honeycomb. The aft bulkhead gives protection against fire. There is a hold-open rod fitting installed at the bottom of the nacelle inlet on the left side (right side for a right engine) of the aft bulkhead. The hold-open rod fitting holds the forward hold-open rod. On the right side (left side for a right engine) of the aft bulkhead, there is a latch fitting to engage the inboard-forward latch-pin of the lower cowl.
The attachment ring is attached to the aft bulkhead, and attaches the nacelle inlet to the engine fan case with bolts, nuts and absorption-spacers. During a fan blade-out event, the absorption-spacers will close and absorb the shock load to keep the nacelle inlet attached.
The inner barrel has the acoustic treatment to decrease the fan noise. It gives the correct airflow to the engine fan duct and core. The inner barrel is made from an aluminum skin with small holes, and has a stainless steel mesh which bonds to the inner surface. A two-slot aluminum honeycomb bonds to the outer surface.
The outer barrel gives a smooth aerodynamic external surface between the nose lip and the fan cowl doors. It has a carbon epoxy material with a glass fiber interface. A faying strip attaches to the aft edge of the outer barrel by rivets. The leading edge of the cowls fits tightly on this faying strip.
The outer barrel has a cutout to let TAI air to go through a TAI exhaust duct. A ply of expanded copper foil in the outer barrel skin gives protection against lightning. The outer barrel has a top and a bottom half skin. The bottom half skin has the intake for generator cooling air. An inlet duct is installed in the bottom of the nacelle inlet between the aft bulkhead and the outer barrel. This inlet duct lets cool air into the generator.
The TAI piccolo tube is attached to the forward bulkhead. A bulkhead housing is attached to the top of the aft bulkhead. The inlet duct of the TAI piccolo tube is installed through a metal TAI shroud between the forward and aft bulkheads. A collar attached to the inlet duct of the piccolo tube is installed in the bulkhead housing with two piston rings. The interface between the bulkhead housing and the TAI shroud is sealed by a ring seal.
The TAI exhaust duct is installed in the bottom of the nacelle inlet between the forward bulkhead and the outer barrel. This duct lets used anti-ice air out of the anti-ice annulus. The anti-ice annulus is the area between the forward bulkhead and the nose lip.
System Interface
The thermal anti-ice (TAI) system interfaces with the following systems/components:
- Air Intakes
- Accessory Cooling