Snakes, LUMPs and Quarter Turns

posted on 2nd October 2023
Snakes, LUMPs and Quarter Turns

Airliner-based VIP aircraft require specialist maintenance compared to their commercial brethren. Three industry experts explain how to efficiently maintain, refit and complete your bizliner

When space, comfort and payload are the absolute priorities, only an airliner-based business jet, or ‘bizliner’, will do. Whether an ACJ TwoTwenty or BBJ 777, the base airframe is built to fly thousands rather than hundreds of hours every year and requires careful maintenance.
Tom Chatfield, CEO at Camber Aviation Management, says: “The maintenance schedules for ACJ and BBJ aircraft are adapted to their reduced flight hours, often through a low utilisation maintenance programme, or LUMP, taking into account their unique usage patterns and manufacturer recommendations. Safety and compliance with aviation regulations remain the top priorities, regardless of whether the aircraft is in commercial or private service.”
Chatfield notes a variety of bizliner maintenance schedule modifications. “Time-based maintenance schedules certain tasks based on the number of calendar days or months since the last inspection, rather than flight hours. This ensures critical checks and component replacements are performed regularly regardless of flight frequency.
“Maintenance intervals might also be adjusted based on the ratio of flight hours to cycles. Since ACJs and BBJs are fitted with additional fuel tanks, they have longer range than their airliner brethren and so the ratio of flight hours to cycles will differ.
“Advanced condition-monitoring systems might also be employed, continuously assessing the health of critical systems and components. This real-time data helps optimise maintenance schedules, allowing for predictive maintenance rather than fixed-interval checks.
“Of course, Airbus and Boeing provide specific maintenance recommendations tailored to the unique requirements of their ACJ and BBJ aircraft, respectively, while some operators employ tailored maintenance programmes based on their specific operating conditions, aircraft usage and regulatory requirements. At Camber we recently created a bespoke programme for a client who wanted to maximise availability. It foresees two one-week downtimes a year, resulting in 50 weeks of annual availability.”
Clemens Schrettl, Director Sales VIP & Special Mission Aircraft at Lufthansa Technik (LHT), acknowledges that its customers’ bizliners typically fly between 100 and 800 hours per year, but the airframes are built for 2,000 hours or more. Again, he recommends customised maintenance programmes, further tailored to reflect areas of operation. “The air at high altitude where these aircraft are meant to spend their time is very dry, but VIP aircraft are parked for long periods, sometimes outdoors in high temperatures, but often where it’s very wet or humid and corrosion can be a problem.”
As part of this, he identifies biological contamination as a serious concern. “An airliner is probably refuelled every day and so there’s little potential for anything organic to grow in its tanks. But since some of our VIP customers park their aircraft for weeks and things can grow, in some locations we suggest testing every four weeks to prevent microbial contamination.”
Schrettl also emphasises the importance of parking an aircraft properly, with apertures, engines and other sensitive equipment covered. “You might be surprised at the things we’ve found that like to get inside – it’s not unusual for us to find snakes…” he says.
VIP and special missions are inevitably a niche LHT capability, but thanks to its airline business, its VIP customers benefit from the company’s global MRO presence. That means access to LHT’s maintenance and supply programmes for engines, components, landing gear, rotables and other items, plus AOG support. Schrettl confirms: “We are one of the world’s largest MRO organisations. That means whatever happens, we’ve got you.”

When an aircraft must be down for an extended period of scheduled maintenance, it makes sense to attend to cabin upgrades and repairs at the same time. The process is inevitably complex, however. Chatfield says: “Including maintenance activities alongside a cabin refit involves meticulous planning, collaboration, synchronisation of schedules, shared resources, customised solutions and a commitment to quality control. By capitalising on the synergy between maintenance tasks and cabin work, it’s possible to deliver comprehensive, efficient and cost-effective solutions that enhance both the operational performance and aesthetics of the aircraft.”
A specialist in large VIP completions, refit and maintenance, Citadel Completions is equipped to deliver complete maintenance and cabin packages. Neil Boyle, SVP of Operations and General Manager at Citadel, agrees with Chatfield that there is more to a successful programme than having the tools for the job. “Our team of dedicated professionals is committed to delivering a personalised, exceptional level of quality. We provide an extra level of care and communication that has resulted in long-standing relationships with valued customers who not only rely on us for maintenance but also seek our expertise in cabin and system upgrades.”
Among those upgrades, Boyle says inflight entertainment and cabin management systems (IFE and CMS) are especially significant. These technologies have seen important technical advances and become more user-friendly over the past few years. They are often ripe for replacement, but he warns of challenges in upgrading them alongside aging interiors. “We’ve established a dedicated team that conducts thorough surveys and evaluations of interiors and systems. Through these strategic partnerships, we leverage the assessments to create customised upgrade plans that encompass both the IFE system and soft goods, revitalising the overall look and feel of the aircraft.”
It comes as no surprise that LHT also recommends upgrading while the aircraft is in for maintenance. Schrettl identifies satcom antenna installation as a typical task, alongside cabin refurbishment. The company offers complete maintenance, refurbishment and design capabilities at its Hamburg facility and has a product catalogue that includes dishwasher installations, CMS and emergency cabin floor markings tailored to the cabin finish

Complete service
Boyle and Schrettl say customers regularly select Citadel or LHT to complete their aircraft and then return for scheduled maintenance and refit. “We have some very happy, frequent customers who come back to us for refurbs and, when it’s time for a new aircraft, another completion project,” Schrettl happily reports. “In between, we do base maintenance, sometimes line maintenance, aircraft component supply, engines, almost everything. We even provide line maintenance for some customers at their base, and we can train their people how to maintain a new aircraft, especially the specifics of the VIP fit.”
The need to manage maintenance on a green aircraft during its completion is perhaps less obvious, but nonetheless important. Chatfield again: “Managing the more prosaic items of MRO during the completion of a green airframe can also be a complex task. When a green aircraft enters the completion centre it is first placed into storage, which essentially means performing specific tasks – as directed by the OEM – to preserve the airframe, engines and systems while the outfitting takes place. The completed aircraft is subsequently removed from storage, its systems reactivated and function-checked ahead of the ground and flight testing necessary to certificate the modifications undertaken.
“Airworthiness Directives (ADs) and bulletins issued by aircraft manufacturers are crucial for safety and regulatory compliance. Any new ADs or bulletins applying to the specific aircraft model are assessed by the completion centre and, where applicable, installed during outfitting. Meanwhile, seals, tyres, batteries and other perishable or time-limited components may need replacement or maintenance.
“The wheel assemblies, for example, including the tyres, are either removed and replaced with non-airworthy wheels to preserve the originals, or the aircraft may have to be carefully moved by a quarter turn of the wheels every month to avoid flat spots on the tyres.”
Once again, Chatfield also highlights the importance of communication and careful management to an efficient outcome, saying: “The MRO and completion teams must collaborate so the MRO team can ensure maintenance tasks are integrated into the overall schedule while completion activities progress, preventing conflict or disruption, while rigorous quality control and inspections should be conducted throughout, helping identify and rectify issues promptly and ensuring the aircraft meets safety and quality standards.”
Safety, high quality standards and exceptional customer service are priorities at Citadel too, helping the company win approvals from various agencies, regions and country-specific authorities. It is also part of the ACJ Service Centre Network for MRO and an approved BBJ facility. “We offer extensive service capabilities for both OEMs,” Boyle states, while also noting Citadel’s intention to expand its ACJ business.
Ultimately, achieving quality bizliner MRO and cabin completion or refit requires a holistic approach, preferably guided by expert hands, including those found at Camber, Citadel and LHT. Chatfield has seen owners run into trouble after assigning the wrong person to manage the process. Successfully managing a complex project requires an advanced degree of training, experience and knowledge; whether it’s a completion or refit, with or without additional maintenance, Chatfield says careful completion management is key, while MROs with in-house cabin capabilities help optimise scheduled maintenance downtime.