STC, not as easy as 1,2,3
Upgrading aircraft connectivity isn’t simply plug-and-play – every change comes with paperwork, patience and a supplemental type certificate. Words by Yves Le Marquand
STC, not as easy as 1,2,3
Upgrading aircraft connectivity isn’t simply plug-and-play – every change comes with paperwork, patience and a supplemental type certificate. Words by Yves Le Marquand
Like smartphones and car media systems, in-flight connectivity services are updated and iterated upon every year, often with multiple upgrades coming in a 12-month period.
But being the second-most regulated industry (behind nuclear energy) means adding physical upgrades to an aircraft is not as simple as popping down to the local Apple store or car dealership.
Each upgrade requires a supplemental type certificate (STC). Issued by an aviation regulator, STCs are critical to ensuring any changes made to an airframe — from wireless connectivity points to external antennas — maintain its airworthiness and adhere to safety standards. STCs facilitate innovation while upholding the safety requirements of national aviation authorities, making it important to generate them as new hardware becomes available.
Generating STCs, particularly for connectivity improvements, can help to maintain aircraft value, which is especially relevant if the owner or operator plans to sell the aircraft on. As part of their due diligence many buyers look for STC-backed modifications.
Also, an STC from a major authority, such as the FAA or EASA, can be validated internationally. While making the aircraft attractive to larger group of potential buyers, it also simplifies international operations for owners and operators — critical for those who fly across borders.
But STC generation is not a linear process. It requires careful planning, allocation of resources and patience to navigate through the various stages of certification and can vary depending on the specific jurisdiction and authorities involved.
According to Michael Skov Christensen, chief commercial officer at Gogo, the most recent STC generated by QCM Design in conjunction with ACC Columbia Jet took about 12–16 weeks from inception to final approval.
“MROs or design engineering companies will do a lot of pre-planning to minimise the aircraft downtime. Once final flight testing is complete, it may take as long as two weeks for approval by authorities,” he says. “The more pre-planning that can be done the better.”
Additionally, as an organisation generates more STCs, it better understands the regulations that each certifying authority requires for these programmes, explains Anthony Wiederkehr II, chief operating officer, AeroMech.
“Then we become better at addressing the appropriate regulations for all certifying authorities upfront in the initial STC development programme,” says Wiederkehr. “This streamlines subsequent validation efforts.
“Generally if you are developing an STC for an airframe that is similar to other airframes you have certified, some of the design and substantiation data from previous analogous STCs can be utilised in whole or in part, he adds. What can be utilised is evaluated on a case by case basis and it varies considerably from one programme to another.”
But for operators flying globally, additional complexity arises from differences in regulatory regimes. A system certified in one jurisdiction may still require validation or additional approvals elsewhere, this can impact both upgrade timing and equipment choice.
The exciting and most challenging part is optimising the design for each specific airframe type, explains Wiederkehr. There are generally a few locations you can place the antenna and other LRUs, but the challenging part is determining within the regulations what is optimal for the airframe, customer base and for the companies installing the solution.
“Early in these programmes, our structures, electrical, aerodynamics and manufacturing teams all collaborate to help make the best decisions we can for each airframe type and STC,” he adds.
Gogo does not generate commercial STCs as it is not responsible for the installation of the systems. This is the domain of the MRO or OEM. That said, Gogo works closely with the MRO to ensure they have a full understanding of the system and there is always support on hand for STC generation.
The company works with multiple MROs. Its most recent STCs were granted to companies including Atlas Aviation Service, Trimec Aviation, QCM Design/ACC Columbia Jet and Alamo Engineering. Gogo currently has contracts for 38 STCs for the Gogo Galileo HDX and a further ten contracts to support the FDX variant.
Christensen says challenges are normally associated with modification of an airframe to ensure the system can be equipped safely and within operational parameters. While connectivity is often marketed as if it can be applied uniformly, not every system is compatible with every aircraft type. Differences in size, structure, mission profile and even operator preferences mean that solutions must be customised. A system designed for a large-cabin jet may not be viable for a light aircraft, and vice versa.
In the US, some MRO companies have FAA Organisation Designation Authorisation (ODA) status. Companies undergo meticulous vetting to obtain ODA status, which allows them to conduct examinations and issue certifications subject to ongoing FAA oversight.
AeroMech has ODA status approval to undertake work on more than 50 aircraft models. According to Wiederkehr, the amount of FAA oversight required will vary depending on the STC ODA’s experience and past performance with the scope of work, and resulting approved delegations from the FAA.
“For our programmes, AeroMech controls most of the required approvals utilising appropriately rated AeroMech ODA Unit Members. The FAA retains the right to approve some of the certification documentation and also retains specific technical disciplines such as acoustics compliance,” explains Wiederkehr. “The FAA always has the right to retain additional data approvals if there are particular areas of concern for a given programme.”
Utilising its FAA STC ODA, AeroMech’s recent STC timelines have been anywhere from 4.5 months to 12 months from start to finish.
“It really depends on how much design and substantiation data you have at your disposal that is applicable or relevant to the STC in development. If we are introducing a new antenna, new structural and electrical parts, new design concepts, etc, it generally takes longer,” says Wiederkehr.
This leaves operators facing difficult choices around when to invest in upgrades. With connectivity technology always evolving, there is a risk that a system installed today could soon be eclipsed. Timing upgrades to align with both aircraft utilisation cycles and technology maturity has become a balancing act between staying current and avoiding upgrades that could quickly become outdated.
Gogo’s Christensen says the cost of the STC is normally at the expense of the originator of the STC. Once a company holds an STC it either secures future work installing the STC on the airframe for which the approval is awarded or the STC becomes part of a commercial transaction with another MRO.
Generating STCs is a complex process, but it can be done efficiently if proper planning is in place and enough time is allotted for completion. Regardless, if owners and operators wish to travel internationally, make use of a jet as an airborne office or mitigate asset depreciation then the STC process if vital to undertake.
A guide to the STC process
Start with the airframe: Identify the specific modification you want to make to the aircraft. It is critical to define the scope of the modification and understand its impact on the aircraft’s compliance with regulations.
Paperwork: Detailed documentation including engineering drawings, analysis and test plans is required. The documentation should demonstrate that the modification complies with applicable airworthiness standards and does not compromise safety or performance.
Plan, plan, plan: Develop a certification plan that outlines the steps required to demonstrate compliance with regulations and airworthiness standards. The plan should identify the specific authorities and organisations involved in the certification process.
In addition to documentation, engaging in meetings and discussions and addressing any questions or concerns raised by the authorities is critical.
Testing: Tests and analyses may be required to demonstrate compliance and show that the modification does not negatively impact the aircraft’s performance, handling qualities or safety.
Seek approval: Once all the necessary documentation, tests and analysis are completed, the STC application can be submitted to authorities for approval.
Review and further communication: When aviation authorities review the submitted application, it is common for them to request modifications or revisions to the submitted documentation or certification plan. This can extend the timeline and add complexity but can also be mitigated with clear communication.
Approval: Once issued, the STC provides the official approval for the modification and outlines any limitations or special instructions that must be followed.
