Design and Research of Civil Aircraft Flap/Flap Control Lever Based on Ergonomics

Abstract

The Flap/Slat Control Lever is one of the important controls in the cockpit of a High Lift system. The design of the Flap/Slat Control Lever includes mechanical and electronic design, which needs to meet the requirements of functional interfaces, mechanical interfaces, electronic interfaces, ergonomics, airworthiness, safety, reliability and maintainability. The Flap/Slat Control Lever design is a complex process with multiple rounds of iteration and gradual progress. The overall shape, detent system design must conform to the pilot’s control habits, have good control comfort and accessibility, the shape of the knob is smooth, easy to identify, simple, smooth and accurate operation. The gate design must satisfy the airworthiness regulations. The design process needs to integrate ergonomics, sample collection, evaluation methods, probability statistics and other factors for comprehensive design.

1 Introduction

The Flight Control System mainly comprises Primary Flight Control System and High Lift System, wherein the Primary Flight Control System is mainly used for realizing roll, pitch and yaw control, trim control and air deceleration of an airplane in the air, lifting breaking-up control after the airplane is grounded; The High Lift System is mainly used to control the lift and drag of the aircraft during take-off and landing. The Flap/Slat Control Lever is one of the important control devices of the High Lift System in the cockpit, and the flap and slat surface are positioned at the command position according to the preset speed through the command of the Flap/Slat Control Lever. The design of Flap/Slat Control Lever includes mechanical and electronic design, which needs to satisfy the requirements of functional interface, mechanical interface, electronic interface, man-machine work efficiency, airworthiness, safety, reliability and maintainability.

The design of Flap/Slat Control Lever is a complicated process with multiple rounds of iteration and gradual progress. The overall appearance, detent system design shall conform to the pilot’s control habits, with good control comfort and accessibility. The control lever shall be smooth in appearance, easy to identify, simple, stable and accurate to operate. The detent system design shall meet the requirements of airworthiness regulations. The design process needs to integrate ergonomics, sample collection, evaluation methods, probability statistics and other factors for comprehensive design.

Based on ergonomics design theory and CATIA three-dimensional motion simulation, this paper analyzes the ergonomics characteristics of the Flap/Slat Control Lever of a civil aircraft, and makes a detailed analysis on the overall shape design, detent system design, control force and other details of the Flap/Slat Control Lever.

2 The Design of Flap/Slat Control Lever

The design of Flap/Slat Control Lever includes knob shape, detent system, lifting force and friction force design and so on. At each design stage, ergonomic evaluation needs to be performed in conjunction with pilot evaluation methods.

2.1 Design of the Knob’s Shape

The general shape design of the Flap/Slat Control Lever should meet the following design requirements [1]:

• a) The Flap/Slat Control Lever should satisfy the general shape shown in Fig. 1, but need not be designed to its exact size and specific proportions;

  Fig. 1.

  

  Outline design requirements of Flap/Salt Control Lever

• b) The shape of the Flap/Slat Control Lever should be designed so that mis-operation is unlikely to occur, and measures should be taken to prevent it from being mishandled during flight.

The main design contents of the Flap/Slat Control Lever include:

• a) Movement axis point;

• b) Flap/Slat Control Lever stroke;

• c) Unlocking stroke of Flap/Slat Control Lever;

• d) The distribution angle of the Flap/Slat Control Lever and the angle between two card slot;

• e) Slope of Flap/Slat Control Lever’s knob;

• f) Weight and center of gravity position;

• g) Height of Flap/Slat Control Lever;

• h) Flap/Slat Control Lever knob’s height, width and depth.

Figure 2 shows the outline of a typical Flap/Slat Control Lever.

Fig. 2.

Outline view of a typical Flap/Slat Control Lever

The shape design of the Flap/Slat Control Lever needs to be considered in combination with the unlocking method of the handle operating mechanism. At present, there are two main ways to unlock the Flap/Slat Control Lever of the civil aircraft in service:

• a) Lift up the Flap/Slat Control Lever, as shown in Fig. 3;

  Fig. 3.

  

  Lifting the Flap/Slat Control Lever to unlock

• b) Unlock the locking plate, as shown in Fig. 4.

  Fig. 4.

  

  Flap/Slat Control Lever with locking plate unlocking method

The shape of the handle selected by different aircraft manufacturers has its own characteristics. The shape of the handle directly determines the ergonomics. According to the experience of investigating pilots to operate the Flap/Slat Control Lever in multiple pilot evaluations, we can see that the designer cannot blindly follow the pilot’s opinions to design, because different pilots have different opinions, which is related to their professional background, habits and preference, and the opinions of pilots are not the same all the time. Under different time and different physical conditions, their experience of using the knob is different. Therefore, the designer should consider the pilot’s opinions and their own experience to consider the design.

2.2 The Design of Detent System

Figure 5 is a schematic diagram of a typical Flap/Slat Control Lever detent system design. The specific requirements of the detent system design of the Flap/Slat Control Lever are as follows:

Fig. 5.

Typical detent system design

• a) The design of the detent system and gate should meet the configuration requirements of the flap and slat;

• b) The design of the detent system should be clear, and ensure that the Flap/Slat Control Lever is released from any position, and the handle can automatically be drawn into the adjacent card slot without using external force;

• c) The gate of the Flap/Slat Control Lever should ensure that the handle must have a distinctly different independent movement to move the device through the set position of the handle.

The Flap/Slat Control Lever in Fig. 5 has 4 evenly divided card positions and 2 gate design. The design of the detent system should be designed in combination with the lifting force and the friction force, so that the handle cannot stay between the card positions. According to experience: If the pilot puts the handle near the card position, the handle should be automatically drawn into the adjacent card slot without using external force, instead of staying between the two card positions [2]. There should be a clear position indication on the Flap/Slat Control Lever lighted plate to remind the pilot where the handle is. The lighted plate provides monochromatic light through a light emitting diode (LED), and the brightness can be adjusted to meet the light requirements of different weather. The design of the gates in Fig. 5 are bio-directional gates. That is, when the Flap/Slat Control Lever is operated forward or backward at the position of the gate, it must be drawn into the corresponding slot to continue to manipulate the handle. A gate is a device that must have a distinctly different independent movement in order to move the lever through its set position. The purpose of the gate is to prevent the pilot from malfunctioning and make the lever of the lift device pass the gate [2]. The design of the detent system needs to meet the corresponding airworthiness regulations, which should be clear, specific and reasonable.

2.3 The Design of Feel Force

The feel force design of the Flap/Slat Control Lever should include the unlocking force and friction force of the handle. The design process needs to consider:

• a) The unlocking force of the handle is generally generated by a spring. It is unlocked by lifting the handle or compressing the unlocking plate of the handle, and it should remain unchanged during the entire handle movement. A typical flap/slat handle unlocking force mechanism is shown in Fig. 6;

  Fig. 6.

  

  Typical Flap/Slat Control Lever unlocking force mechanism [2]

• b) The friction of the handle is generally generated by the friction device. When the handle is not moving, the frictional force should keep the handle in the corresponding slot without shifting or shaking; when the handle is moving, the frictional force provides the pilot’s feel force. A typical flap/slat handle friction mechanism is shown in Fig. 7;

  Fig. 7.

  

  Typical Flap/Slat Control Lever friction mechanism

• c) The operating force of the Flap/Slat Control Lever should be smooth without any impact or discomfort; under any displacement and amplitude of the Flap/Slat Control Lever, the minimum speed and frequency of the operating must be guaranteed;

• d) The unlocking force and friction force shall be in accordance with the ergonomic design and guaranteed to remain unchanged throughout the whole life cycle.

2.4 Other Design Requirements

The design of the Flap/Slat Control Lever also needs to meet the following requirements:

• a) The number of sensors shall meet the system redundancy design requirements; The sensor of each position should meet the requirement of accuracy and keep the same in the whole life cycle. The type selection of the sensor should consider the electrical interface, durability, reliability and mechanical environment requirements;

• b) The limited load on the Flap/Slat Control Lever shall meet the requirements of FAR25/JAR25/CCRA 25 parts, such as 25.305 and 25.405;

• c) In order to ensure that the Flap/Slat Control Lever can be easily removed and replaced, the Flap/Slat Control Lever and the lighted plate on the lever can be used as the replaceable parts of the airline to reduce the maintenance cost of the airline and increase the competitiveness of the product;

• d) The connectors shall be designed to avoid to the wrong installation of equipment;

• e) The Flap/Slat Control Lever is installed on the central console of the cockpit, behind the throttle lever, aligned or deviated to the center line of the central console at least 254 mm behind the Landing Gear Control Device;

• f) The Flap/Slat Control Lever shall be designed for easy disassembly and assembly, which can be completed without special openings designed on the central console;

• g) Flap/Slat Control Lever shall meet the requirements of bonding, it is generally recommended to use surface bonding, and special bonding surfaces shall be reserved on the central control table to avoid direct bonding on the surface of the central control table, which the bonding area is too large to be easy for workers to operate, so it is difficult to meet the requirements of bonding. It is not recommended to use the fastener bonding mode, because the mounting force of the handle is too small and changed to meet the bonding requirements;

• h) Commonality shall be considered to ensure the exchange of as many parts, small components or large components as possible.

3 Conclusion

This paper mainly introduces the design process of the Flap/Slat Control Lever of civil aircraft, including the shape design of the Flap/Slat Control Lever, the design of detent system, the design of feel force and sensor design. The design process of the Flap/Slat Control Lever of civil aircraft is a systematic process, which requires the system to consider the functional requirements, ergonomics, airworthiness and other requirements [2]. For the same aircraft manufacturer, it is necessary to consider the commonality of interfaces, electrical plugs, etc., so as to achieve the interchangeability of as many parts and components as possible between serial aircraft and between different series of aircraft, and even the interchangeability of handles, so as to provide its economy and competitiveness.