Misc.

Question 1

Spike Knock

Answer 1

Spike knock occurs when the round pin in the drag-pin fitting contacts the side of the square hole of the pylon stop, which is mounted to the roof. It creates a loud noise and will occur during a rocking of the pylon. The following factors can cause spike knock: low rotor RPM, extreme asymmetric loading, poor execution of an autorotational landing, and low G maneuvers below +.5 Gs.

Spike knock will be more prevalent during zero ground run autorotational landings than for sliding autorotational landings and running landings.

Spike knock in itself is not hazardous but is an indicator of a condition that could be hazardous. If spike knock is encountered, an entry must be made on the DA Form 2408-13-1 to include the flight conditions under which the spike knock occurred. An inspection will be performed by maintenance personnel before continuing.

During landing, starting, and rotor coastdown, spike knock could also occur, especially if there are high winds and/or the elastomeric damper is deteriorated. This type of spike knock is not considered damaging to the aircraft and does not require an entry in DA Form 2408-13-1.

Question 2

Power Check

Answer 2

> 96% torque- normal or shallower than normal approach to landing areas with a surface with obstacle clearance

> 91% torque- no max performance takeoff, no steep approaches

> 86% torque- no max performance takeoff

<85% torque- no restrictions

Question 3

Engine Failure at Cruise dialogue

Answer 3

Rotor RPM in Limits
N1 is stable
Aircraft in trim

Question 4

Loss of Tail Rotor Effectiveness

Ch 8

Answer 4

Loss of tail rotor effectiveness (LTE) is the occurrence of an uncommanded and rapid right yaw rate which does not subside of its own accord and which, if not quickly reacted to, can result in loss of aircraft control.

    - Weathercock stability: 120-240*, Winds will attempt to weathervane A/C into the wind, makes slow uncommanded yaw to left or right
    - Vortex ring: 210-330*, Causes vortex ring state around the tail rotor which causes tail rotor thrust variations; tendency to make uncommanded pitch, roll, yaw; maintaining precise heading will be impossible
    - Disc vortex: 280-330*, Main rotor tip vortices are directed onto the tail rotor; make sudden, uncommanded right yaw which may develop into a spin if uncorrected

Other factors:

• gross weight and density altitude: an increase will decrease the power margin between maximum power available and power required to hover
• low indicated airspeed: Airspeed s below ETL, tail rotor must produce almost 100% of directional control
• power droop

Question 5

Mast Bumping

Answer 5

Mast bumping (flapping-stop contact) is the main yoke contacting the mast and may occur during slope landings, rotor startup/coastdown, or when the flight envelope is exceeded.