Pitch lock mechanism, Other Engineering

PITCH LOCK MECHANISM

The pitch lock mechanism is necessary to cater for the two fine pitch position of 'flight fine pitch' and 'ground fine pitch'. It acts as a safety device designed to prevent the propeller from inadvertently over-running the flight fine pitch position to the detriment of flight safety.

PRINCIPLE OF OPERATION

The pitch change piston is fitted with two pitch stops - the flight fine pitch stop and the ground fine pitch stop. The flight fine pitch stop provides a normal fine pitch angle, whereas the ground fine pitch stop does not arrest the piston movement until the propeller blades turn into the plane of rotation to attain zero pitch angle. To obtain a zero blade angle it follows that the pitch change piston must move beyond the flight fine pitch position and, to achieve this, the flight fine pitch stop must be withdrawn or rendered ineffective whenever ground fine pitch is required. Therefore, the flight fine pitch stop is a flexible arrangement which requires a support to maintain it in the flight fine pitch stop position. When the support shown is withdrawn, the flight fine pitch stop can move down flush with the level of the pitch lock cylinder and the oil pressure acting upon the pitch change piston can now move it forward into the ground fine position. The pitch lock assembly fits inside the pitch change cylinder and the transfer sleeve housing where it connects with the oil tubes to complete the oilways to the PCM.

2322_pitch lock mechanism.png

PITCH LOCK MECHANISM:

When the aircraft is on the ground the undercarriage switch is closed, the flight deck switch completes the circuit to energise the solenoid valve.

The open solenoid valve directs oil pressure to the stop withdrawal piston allowing the spring collect to spring inwards to remove the Flight Fine Pitch Stop.

844_pitch lock mechanism1.png

To enable either flight fine pitch or ground fine pitch to be selected, pitch selection levers are provides. These levers (one for each propeller) are fitted to the main control pedestal in the aircraft cockpit. They are called 'fine pitch stop levers' and they provide the two stop positions required for flight fine or ground fine. The lever position are:

• Stop armed - This is the flight fine position and the stop lever is at the front of the quadrant.
• Stop removed - This is the ground fine position and the stop lever is at the rear of the quadrant.

2000_pitch lock mechanism2.png


To prevent inadvertent loss of propulsive thrust, the pitch stop levers are mechanically inter-connected with the throttle lever so that when all throttle levers are advanced towards open (for max or cruise power) the pitch stop levers must move into the stop armed position. Thus always when the aircraft is flying the flight fine pitch stop is armed.

Posted Date: 9/14/2012 4:01:42 AM | Location : United States







Related Discussions:- Pitch lock mechanism, Assignment Help, Ask Question on Pitch lock mechanism, Get Answer, Expert's Help, Pitch lock mechanism Discussions

Write discussion on Pitch lock mechanism
Your posts are moderated
Related Questions
Calculatethe tax disadvantage to organizing a U.S. business today, after passage of the Jobs and growth Tax relief reconciliation act of 2003, as a corporation versus a partnership

I have a fermenter case study which needs to be completed in the next 16 hours.

Noise reduction The problem of engine noise has always been associated with aircraft. Increases in engine power have given rise to increases in noise and the indications are t


if we are comparing the risk and return of two stocks. what to calculate, what to analyza and what conclude

A 10m diameter circular tunnel is to be excavated in a jointed ground.  The joint sets spaced at 6m are dipping towards the West at 50°.  A horizontal circular tunnel is to be cons

Would you be able to assit me with a 40 question, multiple chioice quiz today ?

Assignment: You are interested in proposing a new venture to the management of your company. Pertinent financial information is given below. BALANCE SHEET Cash 2,000,000 Accounts


how can we find local attraction correction?