To MCAS and beyond…

Boeing completed its initial 737 Max test flight on the 29th June 2020 from Boeing Field to Moses Lake and a series of further flights to come prior to allow the re-certification of the aircraft family. While the initial steps will be to satisfy the FAA and the other aviation authorities around the world two significant work streams will take place:

·        Applying the modifications both physically and the associated documentation to the in-service fleet to get them back to operation with this new standard.

·        Clearing out the parking lots and storage locations at Boeing’s sites in in Washington State and Texas of around 400 aircraft, with almost all complete and ready for delivery, outside of this specific issue.

With such sharp focus on the Airworthiness Directives (AD’s), Service Bulletins (SB’s) and the certification package associated with the Manoeuvring Characteristics Augmentation System (MCAS) from both the authorities and customers, we know Boeing will produce an impressive suite of data to make the deliveries go smoothly. In much the same way as a magician performs a ‘sleight of hand card trick’ it is important to watch what else is happening away from the show centre. We believe the focus of those customers involved in the delivery of these aircraft should focus on the secondary and tertiary elements of the MCAS system and the aircraft being parked for long periods prior to delivery. 

Each and every customer will have its own approach to the acceptance process but we would certainly encourage a risk based assessment on the delivery process. Most operators will have their own risk or safety assessment model and in most examples are a tabular analysis of the scale of impact multiplied by likelihood to produce a score that can be used for balanced comparison of risk.

AviationMover was requested by an aviation consultancy organisation to share its thoughts and experience for its customers when accepting these new aircraft on what to look out for, when they finally start delivering these aircraft. We wanted to share this with the wider 737 customer community of operators and owners, here are some considerations:

Hardware & Software – The physical changes of the MCAS system will drive changes to both hardware and software on the aircraft. Take time to review the mod state of each associated equipment to ensure you have the right version for your pre and post-delivery configuration. This should not be limited to the Boeing manufactured elements but also the vendor components who provide much of the equipment used within the direct system and others that interface with it.

Physical Inspection – Significant system rework will have taken place to support the hardware and software changes. This is likely to mean wiring changes and new installations. The customer acceptance team will have a chance to conduct BITE tests do ensure correct operation but we would encourage that the team physically inspects the areas where reworks have happen. Much of the wiring is premanufactured and installed when access is easy and all too often when specialist working parties conduct their activities in unusual locations things don’t quite go to plan. Consider visual wire routing checks, general wiring installation reviews following best industry practice and EWIS training. Shutdown checks may want to be considered to ensure the redundancy power sources are coming from the correct bus bar in an emergency, it does happen!

Systems checks – Make sure that appropriate systems checks are able to be completed as part of the acceptance validation process. Some operators build their own set of system and BITE tests prior to the demonstration flight to satisfy themselves of the systems and this feels prudent in on initial MAX deliveries. Even if you don’t have the time and resources for such check asking Boeing about whether they have a customer validation process will help flesh out the subject and ultimately build confidence through the delivery stages.

Aircraft Storage – Keeping in mind this aircraft may have been in storage physically in an employee parking lot for some time since its initial production, it is important to understand what storage processes have been applied. While in the production system Boeing can choose its own approach on storage conditions being applied you should review how these may vary from the ones contained within the Aircraft Maintenance Manual (AMM). Ask to review the paperwork, ensure the check frequency are valid and challenge anything that is different from the norm.

Fuel Contamination – Linked with the storage conditions many aircraft may have been stored with fuel at Renton, Boeing field or Everett all are environments that are not really ideal for extended parking given the damp Seattle air and in close proximity to salt water of the Puget Sound. These conditions have an impact on fuel and the systems if not adequately considered and actioned. Make sure you understand what has happened and possible ask for evidence to validate such as a fuel sample check to be taken and tested prior to the demonstration flight.

Mod State – We talked about upgrades within the MCAS system earlier but it is also important to remember that over the years the mod state of the aircraft as a whole has been evolving. Make sure you have the mod standard you want and expect and also make sure the operator’s engineering organisation understand the specific aircraft-wide mode state. Finding that systems now have variations within them can make a big impact for the maintenance and operations teams.

We could provide much extended commentary on this subject but our closing remarks would be to encourage customer to think broadly about the delivery process on these initial aircraft rather than solely focusing in on the issue that brought this aircraft type into glaring focus.

What do you think? Do you have any concerns on B737 Max deliveries? Let us know your thoughts in the comments!

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