Thrust Reverser Actuation System Lock Tester

The subject matter of this specification can be embodied in, among other things, method for testing operation of a thrust reverser actuator lock includes determining, by a controller, that an actuator output of a controllable actuator is at a predetermined first position, locking, by the controller, an actuator lock configured to prevent movement of the actuator output of an actuator away from the predetermined first position, initiating, by the controller, actuation of the actuator output away from the predetermined first position, determining, by the controller based on a position feedback sensor, a second position of the actuator output, determining, by the controller, a nominal condition of the actuator lock based on determining that the second position is within a predetermined threshold distance from the predetermined first position of the actuator output, and providing, by the controller and based on the determined nominal condition, a signal indicative of the nominal condition.

TECHNICAL FIELD

This instant specification relates to test systems for aircraft actuators, more specifically test systems for aircraft thrust reverser actuator system deployment locks.

BACKGROUND

Contemporary aircraft engines may include a thrust reverser actuation system (TRAS) to assist in reducing the aircraft speed during landing. Typical thrust reversers include a movable transcowl that, when in the active position, reverses at least a portion of the airflow passing through the engine.

Accidental or inadvertent activation and deployment of thrust reversers at inappropriate times can be dangerous or deadly. Accidental deployment on the ground while ground crews are performing service on the engine can result in injury or death. Accidental activation during flight can cause a catastrophic loss of airspeed or failure of the airframe. Mechanical malfunctions, such as a loss of hydraulic pressure, can also allow a reverser to move out of the stowed position at an inappropriate time.

To prevent accidental or unintentional thrust reverser deployment, locking mechanisms are used. Before the thrust reverser can be moved from its stowed position, the lock must first be disengaged. Such locking systems are typically tested periodically, while the aircraft is on the ground, in order to verify proper lock operation or to identify lock malfunctions.

Prior testing processes can be very manual in nature. In an example of a prior process, a circuit breaker is manually opened in order to intentionally prevent an electrical unlock signal from reaching the lock, then the actuator is actuated toward deployment, and then deployment is observed manually, either through direct observation of the actuator or through observation of a sensor indicator. If the lock mechanism is functioning properly, the still-locked lock will prevent substantial movement of the actuator away from its stowed position. Observation of substantial movement of the actuator during the test is indicative of a malfunction somewhere in the system.

Such manual processes can be time consuming and can require the attention of multiple service personnel. For example, air regulations may require an electrical specialist to open the circuit breaker, another person may be required to trigger the deployment from the cockpit, another person may be needed on the ground to observe the actuator, the electrical specialist may be required to close the circuit breaker, and yet another person may be needed to verify that the circuit breaker and the actuator have been returned to a safe and airworthy state.

SUMMARY

In general, this document describes test systems for aircraft thrust reverser actuator system deployment locks.

In a general example, a computer-implemented method for testing operation of a thrust reverser actuator lock for an aircraft thrust reverser actuation system includes determining, by a controller, that an actuator output of a controllable actuator is at a predetermined first position, locking, by the controller, an actuator lock configured to prevent movement of the actuator output of an actuator away from the predetermined first position, initiating, by the controller, actuation of the actuator output away from the predetermined first position, determining, by the controller based on a position feedback sensor, a second position of the actuator output, determining, by the controller, a nominal condition of the actuator lock based on determining that the second position is within a predetermined threshold distance from the predetermined first position of the actuator output, and providing, by the controller and based on the determined nominal condition, a signal indicative of the nominal condition.

Various examples can use some, all, or none of the following features. The method can include storing, by the controller, a value representative of the nominal condition. The method can include determining, by the controller, a malfunction condition of the actuator lock based on determining that the second position is outside of the predetermined threshold distance from the predetermined first position of the actuator output, and providing, by the controller, a signal indicative of a malfunction condition of the actuator lock. The method can include storing, by the controller, a value representative of the malfunction condition. The actuator output can be moveable from the predetermined first position through an operational distance to a predetermined third position, and the predetermined threshold distance is less than the operational distance. The position sensor can be configured to detect movement of the actuator output away from the predetermined first position. The method can include receiving a test initiation signal, where the controller is configured to perform the locking based on the received test initiation signal. The method can include determining, by the controller, one or more of a predetermined aircraft operational state, a predetermined time interval, or a predetermined aircraft operational status, where the controller is configured to perform the locking based on the predetermined aircraft operational status, the predetermined time interval, or the predetermined aircraft operational status.

In another general example, a test system for testing operation of a thrust reverser actuator lock for an aircraft thrust reverser actuation system includes a controllable actuator configured to actuate an actuator output between a predetermined first position and a second position different from the predetermined first position, an actuator lock controllable to a locked configuration configured to prevent movement of the controllable actuator output beyond a predetermined distance away from the predetermined first position toward the second position, and an unlocked configuration in which movement of the actuator output beyond the predetermined distance is permitted, a position feedback sensor configured to provide a position feedback signal representative of a position of the actuator output, a processing circuit configured to control the actuator lock to the locked configuration, initiate actuation of the actuator output away from the predetermined first position, receive the position feedback signal, determine, based on the received position feedback signal, a third position of the actuator output, determine a nominal condition of the actuator lock based on determining that the third position is within a predetermined threshold distance from the predetermined first position, and provide a signal indicative of the nominal condition.

Various examples can include some, all, or none of the following features. The processing circuit can be further configured to store a value representative of the nominal condition. The processing circuit can be further configured to determine a malfunction condition of the actuator lock based on determining that the second position is outside of the predetermined threshold distance from the predetermined first position of the actuator output, and provide, by the controller, a signal indicative of a malfunction condition of the actuator lock. The processing circuit can be further configured to store a value representative of the malfunction condition. The actuator output can be moveable from the predetermined first position through an operational distance to predetermined third position, and the predetermined threshold distance is less than the operational distance. The position sensor can be configured to detect movement of the actuator output away from the predetermined first position. The actuator can be a thrust reverser actuator of a thrust reverser actuator system, and the actuator lock is a thrust reverser actuator system lock.

In another general example, a non-transitory computer storage medium is encoded with a computer program, the computer program comprising instructions that when executed by data processing apparatus cause a data processing apparatus to perform operations including determining that an actuator output of a thrust reverser actuator is at a predetermined first position, locking a thrust reverser actuator lock configured to prevent movement of the actuator output away from the predetermined first position, initiating actuation of the actuator output away from the predetermined first position, determining, based on a position feedback signal, a second position of the actuator output, determining a nominal condition of the thrust reverser actuator lock based on determining that the second position is within a predetermined threshold distance from the predetermined first position of the actuator output, and providing, based on the determined nominal condition, a signal indicative of the nominal condition.

Various examples can include some, all, or none of the following features. The operations can include determining a malfunction condition of the thrust reverser actuator lock based on determining that the second position is outside of the predetermined threshold distance from the predetermined first position of the actuator output, and providing a signal indicative of a malfunction condition of the actuator lock. The actuator output can be moveable from the predetermined first position through an operational distance to a predetermined third position, and the predetermined threshold distance is less than the operational distance. The data processing apparatus can be a thrust reverser actuator system controller.

The systems and techniques described here may provide one or more of the following advantages. First, a system can provide automated testing of thrust reverser actuation system locks. Second, the system can be configured to perform lock testing based on time intervals and/or aircraft state. Third, the system can perform lock testing without the need for multiple human operators. Fourth, the system can perform lock testing without requiring manual recertification that the aircraft has been returned to safe flight status. Fifth, the system can perform lock testing without requiring full actuator deployment. Sixth, the system can reduce the amount of operational downtime required to perform lock testing.

DETAILED DESCRIPTION

This document describes systems and techniques for testing aircraft thrust reverser actuation system (TRAS) deployment locks. In general, TRAS locks include a mechanical latch or catch that is configured to interfere with a portion of a TRAS actuator output. During normal (e.g., intentional, proper) deployment, the lock is unlocked so as to not interfere with movement of the actuator output. Accidental deployment is prevented because movement of the actuator output is mechanically prevented by the lock.

Actuation of the lock mechanism can be monitored through the use of a sensor. However, there are malfunctions that can occur that prevent accurate sensing of lock position and the operational status of the lock. For example, the sensor may be configured to sense movement of a portion of the lock away from a lock finger or other portion of the lock that provides the mechanical interference that prevents actuator movement. If the lock finger is broken, then it is possible that the lock could still appear to be locked (e.g., from the perspective of the sensor), while no longer having the mechanical ability to prevent inadvertent deployment of the actuator output.

Tests to confirm the mechanical capabilities of the lock can be performed in which intentional deployment of actuator output while in the locked state is attempted. If little or no movement of the actuator output away from the stowed state is detected by a sensor, then it can be deduced that the lock has performed its function. If significant movement of the actuator output is detected in the locked configuration, then it can be deduced that a malfunction has occurred (e.g., the lock may have a mechanical failure).

FIG.1is a schematic diagram that shows an example of a thrust reverser actuator lock system100for a thrust reverser actuation system.FIG.2shows the example lock system100in operation during actuator deployment.FIG.3shows the example lock system ofFIG.1functioning to prevent actuator deployment.

The lock system100includes a controllable actuator110configured to actuate an actuator output112. The actuator110is configured to move the actuator output112from a predetermined stowed position or configuration, through a predetermined intermediate position or configuration, different from the stowed position, toward a deployed position or configuration. In the illustrated example ofFIG.1, the actuator output112is shown in the predetermined stowed position.

The lock system100also includes an actuator lock120that is controllable between a locked configuration, as shown inFIGS.1and3, configured to prevent movement of the controllable actuator output112beyond a predetermined threshold distance200away from the predetermined stowed position ofFIG.1toward the deployed position, as shown in the example configuration ofFIG.3, and an unlocked configuration in which movement of the actuator output beyond the predetermined distance is permitted, as shown in the example configuration ofFIG.2.

A position feedback sensor130(e.g., a position sensor) is configured to provide a position feedback signal132representative of a position of the actuator output112. For example, the position feedback sensor130can be a proximity switch, a Hall Effect sensor, an optical detector, or any other appropriate form of contact or non-contact based form of proximity or distance sensor that can be used to determine a relative or absolute position of the actuator output112. A position feedback sensor140(e.g., a position sensor) is configured to provide a position feedback signal142representative of a position or configuration of the actuator lock120(e.g., to sense whether the actuator lock120is locked or unlocked). The lock system100includes a controller150or other data processing apparatus. The controller150includes a processing circuit configured to receive the position feedback signal132and control the actuator lock120.

In the example ofFIG.2, the controller150has commanded the actuator lock120to an unlocked configuration, as indicated by arrow210. The controller150has also initiated actuation of the actuator output112away from the predetermined stowed position ofFIG.1. In the unlocked configuration, the actuator lock120triggers the position feedback sensor140(as represented by arrow220) to send the position feedback signal142to the controller150to indicate that an unlocked state of the actuator lock120has been sensed. With the actuator lock120in the unlocked configuration, a retaining pin114of the actuator output112is allowed to escape the actuator lock120, and the actuator output112is able to move (e.g., rightward in the illustrated example), as indicated by arrow230.

In the illustrated example, the controller150receives the position feedback signal142and can correctly determine the unlocked configuration of the actuator lock120. The controller150also receives the position feedback signal132and can determine that the actuator output112has moved away from the stowed configuration. The controller150is also configured to provide a signal152indicative of the nominal condition (e.g., to the flight or maintenance crew, to a maintenance monitoring system). The controller150is configured to store a value representative of the nominal condition.

FIG.3shows an example of the lock system100with the actuator lock120operating nominally to prevent deployment of the actuator110. In the illustrated example, the controller150has commanded the actuator lock120to the locked configuration ofFIGS.1and3. Actuation of the actuator output112is initiated in an attempt to urge movement of the actuator output112away from the predetermined stowed position ofFIG.1. In the illustrated example, movement of the actuator output112is stopped by the pin114and the actuator lock120, with mechanical interference occurring at a contact point300, thus preventing further extension of the actuator110.

The controller150is configured to determine that the actuator lock120is in the locked configuration based on the position feedback signal142. The controller150is also configured to determine, based on the received position feedback signal132, a position of the actuator output112. If the controller150determines that the actuator lock120is locked and determines that the actuator output112has remained sufficiently close to the stowed position (e.g., within the predetermined threshold distance200) based on the position feedback signal132, then the controller150determines a nominal (e.g., functional, normal) operational condition of the actuator lock120. The controller150is configured to provide the signal152indicative of the nominal condition (e.g., to the flight or maintenance crew, to a maintenance monitoring system). The controller150is configured to store a value representative of the nominal condition.

FIG.4shows the example lock system100in an example malfunction configuration. In the illustrated example, the actuator lock120, identified as120′, is broken in a way that can allow the pin114to escape the actuator lock120when the lock actuator is otherwise in the locked configuration. In another example, the actuator lock120can be intact, but the pin114may be broken (e.g., sheared off) to permit unwanted movement of the actuator output112out of the actuator lock120and away from the stowed configuration, as represented by arrow400, beyond the predetermined threshold distance200.

In some implementations, the predetermined threshold distance200can be less than the distance of full deployment. For example, the position sensor30can be configured such that the predetermined threshold distance200is slightly further away from the stowed configuration that the actuator output112can travel when the actuator lock120is locked and functioning nominally. In such an example, a relatively small amount of movement of the actuator output112can be sufficient to trigger the position feedback signal132, and the testing process can be performed in a relatively shorter amount of time (e.g., because the test does not require the time needed for the actuator110to fully travel to the deployed state and return to stowage).

In previous solutions, determination of similar malfunction conditions was a highly manual process, in which unlocking of an actuator lock would be prevented (e.g., by opening a circuit breaker on a lock actuation circuit), triggering deployment of an actuator output, and then manually observing lack of actuator movement as an indicator of nominal lock operation, or manually observing actuator movement as in indicator of a malfunction of the lock. In addition to any repair that may be needed to the lock actuator, the manual alterations to the aircraft configuration would typically have to be manually returned to operational status and then manually inspected, confirmed, and approved before the aircraft was returned to flight service.

In the illustrated examples, lock test operations can be performed in a pre-approved, repeatable, and automated configuration. In the example ofFIG.3, the breakage of the actuator lock120′ can be detected based on the position feedback signal132and the position feedback signal142. The controller150can determine movement of the actuator output112beyond the predetermined threshold distance200based on the position feedback signal132, despite the position feedback signal142indicating that the actuator lock120′ is in what is intended to be the locked configuration. Based on such discrepancy, the controller150is configured to provide a signal152′ indicative of a malfunction condition (e.g., to the flight or maintenance crew, to a maintenance monitoring system). The controller150is configured to store a value representative of the malfunction condition.

FIG.5is a flow chart that shows an example of a process500for testing a lock system for a thrust reverser actuation system. In some implementations, the process500can be performed by all or part of the example lock system100(e.g., the example controller150).

At505, a controller determines that an actuator output of a controllable actuator is at a predetermined first position. For example, the controller150can receive the position feedback signal132and determine that the actuator output112is in the example stowed configuration ofFIG.1.

At510, the controller locks an actuator lock configured to prevent movement of the actuator output of an actuator away from the predetermined first position. For example, the actuator lock120is configured to selectively allow and prevent movement of the actuator output112away from the example stowed configuration ofFIG.1. The controller150can command the actuator lock120to the example locked configuration ofFIG.1.

In some implementations, the process500can include receiving a test initiation signal, where the controller can be configured to perform the locking based on the received test initiation signal. For example, the controller150can receive an input from an operator (e.g., pilot, aircraft mechanic) or an automated system (e.g., a timer, a state machine) indicative of a request to perform a test of the example, lock system100, and respond by initiating step505and/or510.

In some implementations, the process500can include determining, by the controller, one or more of a predetermined aircraft operational state, a predetermined time interval, or a predetermined aircraft operational status, where the controller is configured to perform the locking based on the predetermined aircraft operational status, the predetermined time interval, or the predetermined aircraft operational status. For example, the controller150can be configured to perform the process500in response to a user input, in response to detecting that the aircraft is safely on the ground and stationary, in response to determining that a periodic service interval is due (e.g., once per flight, once per day, once every 100 flight hours), as part of a pre-flight or post-flight check procedure, and/or any appropriate combination of these and any other appropriate determinable state of time and/or the aircraft.

At515, the controller initiates actuation of the actuator output away from the predetermined first position. For example, with the actuator lock120intentionally left in the example locked configuration, the controller150can command deployment of the actuator output112away from the example stowed configuration (e.g., toward deployment).

In some implementations, the actuator output can be moveable from the predetermined first position through an operational distance to a predetermined third position, and the predetermined threshold distance is less than the operational distance. For example, the actuator output112can be actuated from the stowed configuration (e.g.,FIG.1) and toward a deployed configuration, passing through an intermediate configuration at the predetermined threshold distance200.

At520, the controller determines a second position of the actuator output based on a position feedback sensor. For example, the controller150can receive the position feedback signal132to determine whether or not the actuator output has moved beyond the predetermined threshold distance200in response to the commended movement.

In some implementations, the position sensor can be configured to detect movement of the actuator output away from the predetermined first position. For example, the position feedback sensor130can be configured to detect movement of the actuator output112away from the example stowed configuration (e.g.,FIG.1) and beyond the example predetermined threshold distance200(e.g.,FIG.4).

At530a determination is made. If the second position is within a predetermined threshold distance from the predetermined first position of the actuator output, then at540a nominal condition is determined. For example, the controller150can receive the position feedback signal132and determine that the actuator output has not moved beyond the predetermined threshold distance200in response to the commanded movement, and determine that the substantial lack of output movement is a nominal (e.g., expected, normal function) behavior of a functioning (e.g., not broken) lock system.

At542, the controller provides a signal indicative of the nominal condition, based on the determined nominal condition. For example, the controller150can send the signal152.

If, at530, the second position is outside of the predetermined threshold distance from the predetermined first position of the actuator output, then a malfunction condition is determined. For example, the controller150can receive the position feedback signal132and determine that the actuator output has moved beyond the predetermined threshold distance200in response to the commanded movement, and determine that the excessive output movement is a malfunction condition or behavior of the lock system100.

At532, the controller provides a signal indicative of a malfunction condition of the actuator lock. For example, the controller150can send the signal152′.

In some implementations, the process500can include storing, by the controller, a value representative of the malfunction condition. For example, the controller150can record data to a log or database to indicate the detection of the nominal condition and/or the malfunction condition. In another example, another computer system can receive the signal152and/or152′, and store a value in volatile memory, non-volatile memory, or record the value(s) on an electronic storage medium to represent the identified condition(s).

FIG.6is a schematic diagram of an example of a generic computer system600. The system600can be used for the operations described in association with the example process500ofFIG.5according to an example implementation. For example, the system600may be included in the example controller150ofFIGS.1-4.

The system600includes a processor610, a memory620, a storage device630, and an input/output device640. Each of the components610,620,630, and640are interconnected using a system bus650. The processor610is capable of processing instructions for execution within the system600. In one implementation, the processor610is a single-threaded processor. In another implementation, the processor610is a multi-threaded processor. The processor610is capable of processing instructions stored in the memory620or on the storage device630to display graphical information for a user interface on the input/output device640.

The memory620stores information within the system600. In one implementation, the memory620is a computer-readable medium. In one implementation, the memory620is a volatile memory unit. In another implementation, the memory620is a non-volatile memory unit or a non-transitory computer storage medium.

The storage device630is capable of providing mass storage for the system600. In one implementation, the storage device630is a computer-readable medium. In various different implementations, the storage device630may be a floppy disk device, a hard disk device, an optical disk device, or a tape device.

The input/output device640provides input/output operations for the system600. In one implementation, the input/output device640includes a keyboard and/or pointing device. In another implementation, the input/output device640includes a display unit for displaying graphical user interfaces.