T-45 Engine in a PSG/Spin

Aero Chapter 03, High AOA/Stall/Spin

T-45 Aerodynamics Student Workbook

The proper recovery from a spin is described and detailed in NATOPS. The departure/spin procedure

must be memorized and understood.

T-45 ENGINE IN A PSG/SPIN

An engine anomaly will usually occur during PSGs and spins. An inverted spin will likely result in either a

flameout or surge, regardless of power setting. Although less likely in an upright spin, an engine anomaly

may occur if the upright spin was entered above 25,000 ft or at a power setting above idle. Engine EGT

and rpm should be monitored after departure/spin recovery to determine engine status.

SPIN INDICATIONS

Visual cues may deceive the pilot during the spin. The best spin information is obtained from the cockpit

instruments. The pilot must systematically check altitude, airspeed, AOA, and turn needle to determine the

proper spin recovery procedures.

The altimeter should be the pilot’s first reference in a spin to determine if sufficient altitude remains to

affect recovery. The airspeed would be less than 200 kts in a spin, but an airspeed less than 200 kts does

not necessarily mean you are in a spin. The angle of attack indicator will indicate whether the aircraft is in

a post-stall gyration in an upright or inverted spin, or if recovery is indicated. The turn needle always

indicates the direction of the spin. If the turn needle and/or AOA is fluctuating, the aircraft most likely is in

a post-stall gyration.

A lot is happening very fast, and forces on the pilot may be disorienting. The above instrument scan is a

repetitive process. Once applied, give the controls time to take effect. Time is not passing as fast as it

seems.

SPIN

SPIN TYPE

INDICATOR\TYPE

UPRIGHT

INVERTED

AOA

28 - 30

0

Airspeed

100-180

60-200

Altimeter

Decreasing rapidly

VSI

> 6,000 fpm descent

Turn Needle

Full in direction of spin

g’s

positive

negative 1-1.4

Recovery AOA

decreasing past 20 units

increasing past 5 units

TRUE ANGLE OF ATTACK

True angle of attack is the angle between the relative wind passing the aircraft and the chord line of the

wing. In an upright spin, the true angle of attack will be at or above 30 units and is considered positive. In

an inverted spin, the relative wind will impact the other side of the chord line, and the angle of attack is

considered negative.

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