QMT Features: March 2008
BAE paradigm shift
Getting the right metrology solution is critical for the success of the  F-35 Lightning II ( Joint Strike Fighter) as BAE Systems starts to ramp up production to meet its target of one a day by 2015. By Brendan Coyne


BAE Systems   is a Tier 1 partner on the huge US$300 billion F-35 Lightning II programme. Intended to produce an "affordably stealthy" multi-role strike fighter, the F-35 is based on the development of a common airframe with three variants: the F-35A conventional version for the US Air Force; the F-35B Short Take-Off, Vertical Landing for the US Marine and British Royal Navy; and the F-35C conventional carrier-launched version for the US Navy. 

Total aircraft production will be in the order of 2,500 units and may go as high as 3,500 when sales to other international air and navy services, such as Australia, Canada and Israel, are included.

At present, F-35 production is being led by Lockheed Martin, with BAE Systems and Northrop-Grumman playing major supporting roles as key partners on the programme. There are many subcontractors below that, both in the US and in other partner countries.  The BAE Systems work share of the F-35 programme includes the design, development and manufacture of rear fuselage, horizontal and vertical tails and CV wings together with key vehicle and mission systems including fuel, life support and crew escape systems. The System Development and Demonstration, SDD, phase is estimated to be worth $2.4 billion to BAE Systems in the UK and a further $750 million to BAE Systems Inc in North America. Production could be worth $16.5 billion to BAE Systems UK, and a further $4.5 billion in the U.S. These figures do not include export sales, support or upgrade programs.  

Ian Kendall is the Dimensional Management and Producibility Manager for the F-35 programme at BAE Systems’ Salmlesbury site. Ian is the person charged with developing advanced metrology and measurement solutions to support the F-35 programme as it moves out of the SDD phase into production and final assembly.  The challenge - which is a tough one - is to provide the geometrical and structural requirements to meet aircraft functional and physical specifications whilst maintaining safety, integrity and affordability - key characteristics of the F-35 programme. 

Ian Kendall and his team are seeking to develop appropriate metrology solutions within the time frame as production ramps up out of the SDD phase into low rate initial production and then into full rate production, which will peak around 2015
“We’ve got to achieve a massive paradigm shift.  Currently, we are delivering at about the rate of one aircraft every month. Within the next ten years, we’ve got to get to an aircraft a day - that’s a reduction of TAKT time from 21 days to 1 day. Every day we will be delivering and a rear fuselage and a set of horizontal and vertical tails - a huge part of the finished aircraft. At the moment we are in the System Development and Demonstration phase of the programme with 3 aircraft variants developed, and 35 flying and 6 ground test aircraft in build, or planned.
As we progress from low rate initial production to full rate production, we increase volumes, which will have a significant effect on the manufacturing infrastructure and delivery capability of the BAE Systems’ Salmlesbury site.”

An extension to the F-35 new assembly building will be required for the F-35  together with a new dedicated machine shop, doubling the overall size of the machining and assembly facilities. This increase in throughput will have a huge impact on metrology, inspection and measurement approaches. All manufacturing areas will adapt to support a high rate aircraft manufacturing environment. The demand will impact most business processes, but specifically the ability to quickly verify complex parts and assemblies and the processes which produce them.
BAE Systems has undertook a significant amount of manufacturing development to support the programme, such as high speed machining of aluminium, high performance machining of titanium, low observable composite materials, composite bonding, and advanced assembly techniques.  And while a great deal of attention has been paid on developing the manufacturing and assembly capability during the SDD phase,  Ian Kendall states that less attention has been focussed on the metrology and measurement aspects. These now need to be addressed as the JSF-35 programme moves forward to the production phase with very different requirements.

Inspection drivers
The assembly methodology embracing a pervasive variation management approach, enables OML control to levels which will deliver a stringent signature requirement, this in turn will provide the F-35 airframe with a low observeability (stealth) capability.

No hard tooling gauges are used.  Instead a fully digital solution is integrated into the pervasive variation management approaches and advanced machining technologies, delivering Intechangeability for free. 
These are key requirements which drive the need for accurate, repeatable build and inspection control, and hence drive metrology and measurement solutions to meet not only the engineering, but integrity requirements.

Challenges
As mentioned earlier critical key features to be measured on the structures include module mate interfaces, steps and gaps, hole patterns and aircraft surfaces on assemblies, and inner surfaces, complex LO edges, holes, interchangeable hole patterns etc. on detail parts.  Materials include titanium, aluminium and high temperature carbon composites.

“But as we expand, what we don’t want is buildings full of CMMs or similar, where we put all these parts through.  We need to do something different in order to make it affordable, efficient and in line with the takt requirements.
This means moving to more process control and stability techniques, sample inspection and rapid verification / gauging solutions,” says Ian Kendall.
“There is a real challenge here in terms of accuracy, reliability, repeatability, set up, operator skill levels, CAD and manufacturing systems integration etc. Our current metrology and measurement solutions do not meet this challenge.”

At the moment (in the SDD phase of the F-35 programme) the metrology / measurement mix is 100% inspection as BAE Systems try to establish capable manufacturing processes, which is both stable and repeatable.

As examples, laser trackers, portable arm CMMs and CMMs measure the assembly and detail features. Laser tracking is employed on large volume surface form and location, CMMs for hole positions, bore gauges for hole diameters, ultrasonic devices for thickness, gap guns to check panel steps and gaps etc.

This individual feature data must be manually measured, logged and correlated together to an aircraft unit and factory process capability system.  This data is then used to analyse process capability and support inspection levels.
All these activities need to be consolidated into a more repeatable, more automated process. “We know we need to drive more towards process control, so techniques such as Overall Equipment Efficiency (OEE), statistical measurement and statistical sampling of inspection are critical.”

”The challenge now is how to reduce the time it takes to set up and orientate to the tool or the part.  The time it takes to perform the physical inspection, and the time it takes to understand the digital analysis, the time it takes to support decision making with regards to process capability levels and support the formal acceptance criteria - we really need to attack these areas seriously,” says Ian Kendall.

“As metrology technology, software, system and CAD integration develops, we have to use more and more engineering input to support the operators on the shopfloor because of the metrology / software complexity.  Engineers have to support inspection and analysis for long periods of time. This is not sustainable in a production environment. We need to be able to make quick decisions on line about defects, concessions and capability, whether we can move on or whether we need to take corrective action.

We need measurement systems that are simple, operator friendly and lend themselves to rapid decision making at operator level whilst maintaining product integrity. We need to eliminate the high levels of engineering support and intervention .

The SDD environment has needed to be a flexible one, featuring high direct and indirect resources, high accuracies, complex set-ups and long lead times.
As we move into the production phases what is required is still very high accuracy, but featuring low flexibility, simple set-up, simple factory integration at operator level and very short lead times.  It’s a process solution, a systemic solution - not a technology solution. We’re not interested in what the individual piece of technology can do, whether it’s a laser tracker or portable arm or gauge. We’re interested in a systemic solution, fully integrated into the quality and / or factory system. It must be rapid, agile, and operator led,” says Ian Kendall.

“We need to get it back down to the shopfloor and develop very robust and very repeatable processes, where speed of process is of the essence. Inspections must take only minutes as TAKT times come down to one per day,” says ian.
BAE Systems’ approach to developing the capability they need isn’t just aimed at future metrology technologies and capabilities, but also at pragmatic low technology solutions integrated into the business processes at the appropriate points and times.
Is the F-35 paradigm shift achievable? Ian Kendall says that it is. Can BAE Systems and its partners build the aircraft accurately enough to meet the overall requirements?  The proof is already there to see with some four aircraft on the Salmesbury site surpassing all previous quality levels. “We’ve never seen before the high levels of build quality we are achieving on this aircraft,” enthuses Ian Kendall, “Using a fully digital thread, a pervasive variation management approach and advanced manufacturing technologies has delivered an unprecedented level of quality.

If you go down to the Salmesbury shopfloor, the operators will tell you the aircraft is ‘clicking’ together.  However to the question do we have the metrology and measurement solutions in place to meet, build and affordability requirements? The answer is, No [-  and that’s the challenge we’re taking on.  We have developed a vision and underpinning strategy to establish where we need to be in terms of measurement and associated process capability going forward.  The master schedule to deliver the actions to realise the strategy is in place and being worked.” l
email: ian.kendall@baesystems.com
JSF Producibility & Capability Development Manager & Nozzle Bay Door Program Manager

  
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