Publication:Navy Engineering Bulletin March 2006/Flight Test Engineering in the RAN

BY LEUT ANDREW DAWES

In this article I intend provide an insight into the capability represented by RAN FTEs and how flight test engineering directly contributes to operational effectiveness. In doing so, I will outline what flight testing the RAN conducts, what are FTEs and where they fit into the test process, what tools are used to conduct flight test and what happens when the testing is finished.

Flight testing in the RAN

AMAFTU is authorised to conduct flight testing by CAF through a service release, based upon the outcomes of a formal airworthiness board. Based on this authority, AMAFTU is able to plan, conduct and report flight testing activities as an ADF Flight Test Agency. Flight testing activities conducted by AMAFTU can range from ground based trials in hangars at HMAS ALBATROSS and on flight decks alongside to the developmental testing required to define the Ship-Helicopter Operating Limits (SHOL) for the range of RAN aviation capable ships, covering not just Navy aircraft but Army aircraft as well. Additionally, testing of air stores (missiles, countermeasures and torpedoes to name a few) is carried out by AMAFTU, with dedicated support from the Air Stores Certification (ASC) department of the Aviation Operational Support Group (AOSG). AMAFTU is a unique unit in the ADF, offering similar capabilities to the Aircraft Research and Development Unit (ARDU), however with a specific bent towards embarked helicopter operations.

What are FTEs and where do they fit into flight test?

FTEs are specially trained aeronautical and weapons electrical aviation TQ engineers. The training is an intensive, demanding and challenging 12 month course currently conducted at Empire Test Pilot's School in Boscombe Down, United Kingdom. The course is comprises in-depth ground (too many hours to count!) and airborne (typically 100 hours) instruction covering aeronautics, instrumentation, test planning and program management, risk management, certification and test flying. The course is conducted with other FTE and Test Pilot (TP) students from around the world. My course consisted of engineers and pilots from Finland, Pakistan, The Netherlands, United States, United Kingdom, France and Singapore along with RAAF and ARA personnel. Immediately following the period at ETPS, RAN FTEs and TPs then complete 4 months of residential study at Cranfield University (also in the UK) and a research thesis upon return to Australia. The research thesis is addition to employment at AMAFTU and when completed results in the award of a Master of Science in Flight Dynamics.

Flight test is not a simple business, nor is it forgiving. A great deal of preparatory work is required prior to conducting even the simplest test in the hangar, yet alone flying test points in an aircraft. The comprehensive training program undertaken by RAN FTE students at ETPS provides a robust, solid understanding of the careful planning and programming process required to undertake safe and effective flight testing. In the RAN, this skill most necessary for the qualification of our aircraft (along with further developments in Army aviation) to operate from the surface units of the fleet. This qualification process is referred to as a First of Class Flight Trial (FOCFT).

FOCFTs are complex trials that require the harmonious integration of several different organisations /units operating to differing budgetary, schedule, regulatory and political constraints. FTEs effectively link all the stakeholders in the FOCFT process to ensure the effective and efficient use of the time allocated for the trial. The planning for a FOCFT trial commences several months before the scheduled embarkation period, with the issues to be addressed ranging from the development of ship motion limits for aircraft operations, the logistics of getting a complex instrumentation system installed on the ship for the trial, risk assessment of the trial activities and the implementation of effectives safeguards to prevent unsafe occurrences. Overall, each FOCFT activity lends itself well to a project management approach to ensure that the outcomes produced by the trial meet the requirements identified by the tasking authority. Figure 1 illustrates the range of aircraft types that AMAFTU has been working to enhance the embarked capability in recent times.

FIGURE 1: SHOL DEVELOPMENT - CORE SKILLS FOR AMAFTU

The FTEs involvement in the FOCFT process is not limited to the planning however. FTEs form an integral member of the airborne trial crew, directing the conduct of the trial to achieve the necessary test conditions (in terms of sea state, ambient air temperature and aircraft weight for example) and the required test points (defined in terms of wind speed and direction and landing configuration - RAST or unassisted). During each test flight the FTE operates specialised flight test instrumentation that acquires critical parameters related to the operation of the aircraft and essential to defining the eventual SHOL boundaries. These critical parameters include engine power (normally measured as engine torque), engine temperature, engine speed, aircraft control positions (prior to and post any stability augmentation or flight control systems), aircraft attitudes and rates of attitude changes, height and finally fuel state. Fortunately, AMAFTU has dedicated instrumentation engineers and technicians that design bespoke acquisitions systems to reduce the workload of managing what ends up being a large amount of data and allowing the crew to focus on the real-time analysis of results. This approach allows a rapid, yet safe and incremental development of the eventual SHOL to the absolute maximums possible - NO additional margins or 'fat' exist beyond defined SHOL boundaries. Based on a combination of the quantitative data recorded during each evolution and the test pilot's qualitative comments, the test crew debrief and discuss the results prior to requesting the next set of conditions from the bridge. Figure 2 illustrates the flowchart that is used to define the SHOL development process.

For anyone who has been on-board a ship during a FOCFT it will seem a much slower evolution than normal flying operations - this is a result of careful and thorough debriefing and discussion required within the aircraft to ensure that proximity of any limiting conditions are identified at each test point and subsequently approached in a slow and incremental manner. Failure to live by the incremental approach is the ultimate sin in the flight test world and whilst the crew may get away with it at the time, sooner or later the experience at the next point will be less than comfortable - if they are lucky...

FIGURE 2: THE AMAFTU SHOL DEVELOPMENT PROCESS

It's not just FOCFTs however...

Other flight test activities include trials of type certification and acceptance flying (the PS1411 acquired SH-2G(A) and PS1405 modified Seahawk are particularly demanding in this area at the moment) as well as the test and evaluation of in-service modifications. Whilst PS1405 is primarily in the systems test phase at the moment, PS1411 is continuing with basic testing of the air vehicle and associated with this traditional testing is a great deal of FTE and TP work. During the testing conducted as a lead up to the initial award of an Australian Military Type Certificate (AMTC) and Service Release (SR) there was an extensive test program that evaluated almost every aspect of the air vehicle (performance, stability and control and handling qualities), mission systems and an assessment of it's overall role suitability. FTEs were involved in every element of this assessment (along with test pilots and aerosystems qualified observers) to ensure that the final report was a comprehensive, detailed and meaningful assessment of the SH-2G(A) in the Interim Training Helicopter configuration. The results went far to the award of an AMTC and ensured that the Fleet Air Arm was au fait with the capabilities of its newest airborne weapon system.

PS1405 (Seahawk FLIR/ESM Upgrade) is not entirely without FTE demands either, as shown during the recent stores clearance activity. Stores clearance is a specific test program that assesses various aspects of dispensing stores, typically missiles, bombs and drops tanks, but in this case is was to clear the countermeasures dispensing system installed during the modification of the Seahawk. The trial presented the FTE with specific challenges that required a great deal of dedication, patience and planning in order to safely fly test points. In particular, the trial was the first time that the current, state of the art instrumentation system would be installed by AMAFTU in an S-70B-2 and the FTE involved was responsible (in conjunction with the AEO and maintainers at AMAFTU) for conducting Electromagnetic Compatibility (EMC) testing prior to the trial to ensure the system would not affect and not be affected by existing aircraft systems. Overall, the trial was very successful and has contributed significantly to the ongoing development of the capabilities to be introduced by PS1405.

In addition to major project support, FTEs are deeply involved in the assessment of in-service modifications prior to release across an aircraft fleet. These modifications are typically minor in nature, however can be problematic in terms of test requirements and processes and as such require the dedicated attention, or at least some initial investigation by test personnel. This process ensures that any eventual testing that is carried out is relevant, meaningful and ensures the end product meets it overarching role requirements.

FIGURE 3: RAYTHEON - AMAFTU SHOL ENVIRONMENT SOFTWARE

What tools do we use for flight testing?

Aside from TPs, the FTE has a number of tools at his disposal to achieve the requirements of the trials programme. Typically, the most complex involve testing to derive the SHOLs published in ABR 5419. As stated earlier, the aircraft is heavily instrumented to record a number of parameters that will allow both in-flight and post-flight analysis to define the recommended envelope. In-flight the data is used to make critical decisions on which test points to pursue and how to take advantage of the prevailing conditions to further the testing to date. Post-flight, the data is thoroughly analysed independently to make decisions on whether to include or exclude a point in the recommended SHOL envelope.

Figure 3 illustrates the Raytheon -AMAFTU SHOL Environment software (RASE) developed specifically for FOCFT. RASE is an excellent tool for allowing real time analysis to critical aircraft parameters (engine power, aircraft controls and weight) during a FOCFT test point. RASEs usefulness does not end with the flight however, as it is also designed to facilitate relatively straight-forward management of each data point, compiling a picture of the completed points on a SHOL chart for review and analysis.

Figure 4 illustrates the main element of the core system used extensively by AMAFTU for most flight testing - the Integrated Data Acquisition System (IDAS). IDAS is a tailored system, developed in-house by AMAFTU personnel, for installation into the entire fleet of RAN aircraft for either short or long term trials. Currently one system has been installed in an SH-2G(A) for well over 12 months and is critical in the on-going test and evaluation associated with the Sea Sprite during it's introduction into service.

Thankfully, flight test techniques do not always call for complex tools to acquire data - sometimes aircraft gauges, a voice recorder, stopwatch, pencil, paper and ruler are sufficient to meet the trials requirements. However, it all depends on what is required to be done with the data following the flight. In the case of a simple qualitative evaluation of an aircraft or system, the FTE is there to record to test pilot's comments, note general aircraft performance aspects and debrief the test pilot following each point to ensure that accurate data is recorded for easier reporting post-flight.

What do we do when flying is finished?

When the flying is finished the fun for the FTE begins ... Data analysis and reporting are domains in which the FTE is expected to excel. Thankfully this area is as much a team responsibility as the test planning and test conduct is, so the FTE is generally not on their own.

Data analysis, like test conduct and instrumentation, is very much tailored to the trial requirements. In the case of FOCFT detailed analysis of each test point occurs in real time and post-flight to ensure the maximum possible SHOL is derived based on the results obtained within the prevailing test conditions. Classical trials such as aircraft performance or stability and control related assessments, can involved detailed quantitative analysis, ranging from the development of flight manual performance charts to the analysis flight dynamics data, involving time domain based reviews of pilot control inputs to full blown frequency domain work to analyse the performance attainable from a specific control system design. Shown in Figure 5 are a cross section of the results of the FTEs data analysis work in a number of performance and stability and control assessments and investigations undertaken in the previous 12 months.

Like data analysis, the importance of reporting cannot be underestimated, as it is not only the record of what was carried out, but also the information by which various defence authorities make critical decisions. As such, effective concise and clear reporting is a critical skill that all flight test personnel must possess. Reporting is not something that happens overnight either - the last major SH-2G(A) report averaged NINE hours of reporting work for every ONE hour of flight testing! Trials reports take a significant amount of development and review time to ensure that concise, correct and meaningful results are presented to the trial sponsor to ensure the task objectives have been met and the results documented.

FIGURE 4: AMAFTU INTEGRATED DATA ACQUISITION SOFTWARE INTERFACE

FIGURE 5: TYPICAL PERFORMANCE & STABILITY / CONTROL ANALYSIS WORK

Conclusion

FTE's are critical members of the flight test team and are integral to the development of embarked aviation capability with both existing and future platforms. AMAFTU has two FTEs dedicated to FOCFT, in-service trials and support to the major acquisition projects of both Navy and Army. In their short history with the RAN, FTEs have contributed significantly to every element of flight testing, particularly in the

domain of FOCFTs. The future for FTEs in the Fleet Air Arm appears bright, with ongoing service affording the RAN an emergent realisation of the synergies of flight test skills with an engineering background ensuring safe, effective and capability focused testing.