NTPS VSS UH-72 Lakota Installation

U.S. Naval Test Pilot School UH-72 Variable Stability Helicopter Program STATEMENT OF WORK 1.0 INTRODUCTION The U.S, Naval Test Pilot School (USNTPS) trains and graduates qualified engineering test pilots, flight test officers and flight test engineers to conduct test and evaluation at the Naval Air Warfare Center - Aircraft Division (NAWCAD) and other activities, The USNTPS had been operating 2 SH-60B Seahawk helicopters equipped with a Variable Stability System (VSS) designed and built by Veridian Engineering - Flight Research Group (VE-FRG, now Calspan) as an integral part of the Helicopter Flight Mechanics flight syllabus since 1992. Although the system itself has been highly reliable, the SH-60B host airframes were retired. To replace this capability, USNTPS is rehosting the VSS capability in two of their fleet of 5 UH-72 Lakota aircraft. This will allow USNTPS to retain this excellent teaching capability and also provide an opportunity to update the existing capability with new generation hardware and software. The UH-72 Lakota's are derivatives of the Eurocopter EC145 and are operated under a NAVAIR Flight Clearance which is heavily based on an FAA Type Certification to retain parts pool commonality with the commercial fleet. FAA approval for flight of the VSS system equipment installed in the UH-72A will be required at the field level at a minimum. Operational use of the UH-72 using the VSS gain varying capability shall be covered by a NAVAIRSYSCOM Flight Clearance. 2.0 SCOPE This statement of work describes the level of effort required to modify two host UH-72 aircraft to allow in flight variation and monitoring of parameters set forth in paragraph 4.0 by an instructor/safety pilot occupying the right seat of the aircraft. The overall system shall be composed of the following major system elements: - Sensors (VSS system may utilize existing UH-72 sensors if desired) - VSS Computer - Safety Pilot- System Interface - Interface from VSS computer to UH-72 ship actuators - Safety Trip System - Data Recording System The aircraft modification should incorporate the maximum amount of modularity practicable such that the system could be most easily removed and installed in another model UH-72 at some future date. The host helicopter will be GFE. Installation and acceptance testing will be accomplished at The Contractor facility. System testing, development and syllabus development will be at NAS Patuxent River, MD. USNTPS flight crews will perform the flight checkout, with assistance from the contractor pilots as required. 3.0 GENERAL BACKGROUND Similar VSS modifications to two USNTPS SH-60B aircraft were performed under contracts No. N00421-91-R-0127 dated 7 July 1991 and contract No. N00421-91-C- 0127 dated Oct, 1991. 4.0 TECHNICAL REQUIREMENTS The contractor shall determine the technical approach, cost, and schedule, and perform the following tasks to modify the existing UH-72 flight control system to include a variable stability system capability. General VSS Requirements The VSS shall allow the in flight demonstration of the effects of varying stability and control parameters about the pitch, roll, and yaw axes of the aircraft. The variation in flying qualities shall be accomplished by sensing control and flight variables and using those signals to modify the input made to the upper controls using the production aircraft, limited authority, Smart ElectroMechanical Actuator (SEMA) series actuators provided for the pitch, roll, and directional channels. It is required that the system be designed such that one or all axes (Pitch, Roll, Yaw) may be selectively under VSS control. Axes not under VSS control shall use the production control laws for the selected AFCS Mode. The features that can be varied shall include: - Rate feedback (Damping, 3 axes, pitch, roll, yaw) - Attitude feedback - Forward path gain (Sensitivity, 3 axes) - Rate and control coupling to 3 axes and from all 4 axes - Time delay, 3 axes - Forward path lead and lag (1st order, 3 axes) 4.1 Sensor Suite The sensors shall include position sensors for the cockpit controls (cyclic, pedals, collective), attitudes (Euler angles), body rates (pitch, roll, yaw), accelerations nz and ny, angle of attack and sideslip angle. The sensor suite shall be modular such that it can be most easily be transportable from the host modified UH-72 airframe to another UH-72 and shall be compatible with the currently installed USNTPS instrumentation package. The quality and sample rate of the sensor signals must of a high enough quality and sample rate to feed them forward or back to safely and effectively alter the Stability and Control characteristics. The system may use production sensors and their data signals if they are of sufficient quality and sample rate. 4.2 VSS Computers and Electrical Power The computer system that controls the VSS selected features and variation parameters shall be selected to be reliable in a helicopter vibration environment. Also, compactness is highly desired as space available in the H-72 cabin is somewhat limited. Onboard cooling other than ambient airflow is not available. Specific data on the computer environment and space available will be provided by the Government. Power source shall be 28 VDC or ll5V 400Hz. For non-VSS flights, the sensor suite and recording capability shall be capable of powering up without powering the entire VSS system. Actuators The VSS shall use the existing UH-72 series actuators. The transfer of actuator control from the production flight control computers to the VSS computer shall be done without objectionable transients. Once disengaged from VSS control, the SEMA(s) shall revert to the selected production AFCS mode. 4.3 Safety Pilot (SP) to VSS Interface Interfaces from the VSS to the SP shall consist of displays and controls which perform the following functions: - SEMA Actuator Position Indicators - SEMA Actuator Saturation Indications - SEMA Actuator Transfer Fail Indications - VSS System On/Off Indication - Safety Trip Status - SEMA Actuator Engaged Status - Axis Selection - Feature Selection - Gain Selection Existing USNTPS instrumentation package control panels and displays (with perimeter softkeys) shall be utilized to the greatest extent practicable. Controls for changing existing configurations and system engagement and disengagement shall be accessible without the safety pilot removing his hands from the primary flight controls to the maximum extent practical. Functional reach data for the safety pilot will be provided by the government. The system shall provide a mechanical or software locking capability to prevent unqualified crew activation of the installed VSS system. 4.4 Safety Trip System The safety trip system shall consist of an automatic mode and a manual mode. The VSS helicopter shall revert to the selected production AFCS condition following a trip and shall fade to that condition in a smooth fashion to avoid abrupt inputs to the upper flight controls. The automatic mode shall have the following inputs for processing automatic trips: VSS digital computer "watchdog" Pitch SEMA Servo Error Roll SEMA Servo Error Yaw SEMA Servo Error Mast Moment Exceedance Spare input capability for future identified safety trips There shall be a switch to manually disengage the VSS on the flight control inceptors for both the safety pilot and evaluation pilot. An audio tone and light shall be activated when a trip of either type occurs. 4.5 Data Recording System The host aircraft will already have a data recording system installed. The VSS shall provide an ARINC 429 data stream containing VSS unique parameters (gains, selected features, safety trip codes, etc) for recording by the existing system. The contractor shall provide an interface control document (ICD) of the provided bus. The Navy will provide the parameter details on the data required in a separate document. 5.0 TASK DESCRIPTION 5.1 TASK 1 - Design Fabrication, and Installation System design, fabrication and installation of the VSS in the UH-72 shall include: 5.1.1 Design of the system to provide the functions and features described in paragraph 4.0. Design Reviews shall be utilized as required by the SETR process. 5.1.2 Fabrication of the system sensors, computers, wiring, controls, displays, and electronic enclosures. 5.1.3 Installation of the system in a USNTPS provided UH-72 helicopter. 5.1.4 Provide support documentation for the VSS equipment in the form of 5.1.4.1 Detailed functional block diagrams of signal flow through the VSS. (CDRL A00I) 5.1.4.2 Block diagram, schematics, and front views of any analog signal conditioning devices (CDRL 002) 5.1.4.3 Wiring cables and their physical location in the host UH-72. (CDRL A003) 5.1.4.4 Check out procedures (CDRL A04) 5.1.4.5 A top level troubleshooting guide suitable for use by operational level maintenance personnel which references the publications mentioned in 5.1.4.1thru .4 (CDRL A005) 5.1.4.6 Procedures and instructions for removal and reinstallation of the VSS in the host UH-72 and/or another UH-72. (CDRL A006) 5.1.4.7 Operating Instructions (CDRL AO007) 5.1.4.8 Field level FAA certification for the hardware and provisions of the VSS installed in a Navy UH-72 (CDRL A008 - optional). 5.2 Task 2 - System Ground and Flight Checkout VSS ground and flight checkout shall include the following: 5.2.1 Perform briefings for USNTPS project personnel on operation of the system. 5.2.2 Provide technical and maintenance support for system debugging, adjustment, flight preparation, flight test operations, for 10 hours of flight acceptance evaluations. 5.2.3 Proposed test plan for ground evaluation and check-out. (CDRL AOO5) 5.2.4 Proposed test plan for flight evaluation and check-out (CDRL AOO9). 5.3 Task 3 - Field level FAA approval of the VSS installation. 5.3.1 Operation of the UH-72 using VSS capability will be also covered under a NAVAIR Flight Clearance. However, The Contractor shall provide data and analyses for NAVAIR Airworthiness review. Specific data and analyses to be provided will be detailed in a separate document once the design is more mature.