Avionics 101: Pre-Purchase Avionics Inspections

Over a series of articles Ken Elliott covers the different aspects of Avionics, where they may be relevant to an aircraft owner, operator, buyer or a broker. Here, he discusses the technical characteristics of avionics that may be considered during an aircraft transaction.

Ken Elliott  |  25th June 2021
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    Ken Elliott
    Ken Elliott

    Ken Elliott is a veteran with 52 years of aviation experience, focussed on avionics in General and Business...

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    Private jet flight panel with avionics lit up

    When acquiring a business jet, avionics is just one of several areas to address. Despite its importance, it is not always prioritized correctly. Understanding avionics is both a science and an art because there are numerous integration nuances and equipage options that can vary considerably. Ken Elliott explores...

    A knowledgeable aircraft consultant may be capable of leading the owner or buyer through the avionics maze, but becoming familiar with some of the fundamentals yourself – as a current or future owner – provides for an educated confidence to probe and ask the right questions along the way.

    Checklist for Avionics

    A smart way to address the aircraft’s avionics during a transaction is to work from a checklist. Table A provides an example checklist to assist you with the avionics requirements.

    TABLE A: Avionics Checklist for a Pre-Purchase Inspection

    An aircraft trade is a process that is likely to include a pre-purchase inspection, repairs and routine maintenance before the aircraft delivery takes place.

    For convenience, this checklist assumes there will be no major upgrade or modification undertaken. However, some transactions do involve an upgrade to the avionics, which will be addressed in a future article.

    Table A is somewhat exhaustive, and could seem overwhelming, but it’s worth noting that not all items will apply to every aircraft. Many other items will only entail a check to ensure they are completed, with no work steps required.

    How to Approach the Checklist

    An approach to the checklist is to think in terms of:

    a)    Maintenance for Airworthiness

    b)    Approval for Operations

    Both the airworthiness and the operations consist of ‘on and off’ aircraft tasks. The on-aircraft tasks may be as simple as checking for a part number, modification status, serial number or software level. On-aircraft tasking also refers to tests conducted with ground power and tests conducted while airborne.

    Off-aircraft tasks can mostly take place in a flight department conference room, for example checking logbooks and other aircraft records.

    How a  jet for sale has been maintained can be reflected in the state of its records. Shabby, incomplete records thrown in a box and buried inside a hangar cabinet may well be an indication of an aircraft not being consistently maintained.

    With avionics, record-keeping is paramount as there are so many remote rack-mounted systems and assemblies, each with their own history.

    When reviewing logbooks, if you see a lot of entries for the same component (maybe different serial numbers) being repaired or swapped, that could be a red flag. Here may be a bigger problem that is aircraft (not box) related. This may require expert troubleshooting.

    In this case, be sure to ask if the reported problem was ever properly resolved, and if it’s intermittent, how often is it still occurring?

    Equip to Function Where you Will Operate

    Looking at ‘Operations as Applicable’ check items on Table A, the goal is not to look at how the aircraft was approved previously, but what it needs to be approved for next.

    When traded, an aircraft may be operating in a completely different environment, where different rules apply. Different operating rules signal different equipage, or different versions of equipage. You may indeed have the product on the aircraft equipment list, but that does not automatically mean it is approved to operate in any airspace.

    Not only does the approval require the right version of the product, but it dictates both the aircraft is approved and the crew are trained. In essence, the flight department as a complete operating entity, is what the approval applies to.

    Some examples of inadequate approval are:

    • That the aircraft is only provisioned and not fully equipped. Boxes are missing, power breakers are pulled and tied back!
    • The equipment is installed but requires a hardware or software change to operate in the airspace you intend to fly.
    • The equipment is fitted and current, but awaiting a final airworthiness certification – and the aircraft has an exemption to operate, pending final approval.
    • The equipment is installed with the latest version of software, but the crew have not been trained and certified for the specific type of operation to be flown.

    A great example of equipage operational approval is the ADS-B Out worldwide requirement. There are two versions of ADS-B Out (Version 1 and 2).

    Proactive OEMs may have previously equipped their new aircraft with Version 0 (sometimes termed 1) not fully-aware that Version 2 was on the horizon. Those aircraft need to have been upgraded to Version 2, to operate in airspace regions where Version 2 has since become a requirement. Some regions were, and still are, okay with Version 0 (1) ADS-B.

    This is all fine until those aircraft with ADS-B Version 0 (1) are traded into a different region. Some operators have been caught short on this nuance that is not easy to catch ahead of time.

    Incomplete Avionics Records

    Any missing or inaccurate aircraft record should raise suspicion and that is no different for the avionics. Avionics have routine tests to maintain currency and accuracy. Some of these (such as RVSM and ADS-B) can be arranged during routine flights, while others require a visit to the avionics shop.

    While FAR 91-411 and -413 biennial inspections are rarely overlooked, batteries in ELTs and CVR/FDR underwater beacons may be.

    Anything related to aircraft modifications should be scrutinized. Here are several items to check:

    1. Approvals and certificates relating to the modification, from FAA Form 337, or equivalent, to a Supplemental Type Certificate (STC).
    2. Custom prints and data showing new equipment wiring and locations.
    3. Electrical Load Analysis that includes all modifications to date.
    4. Weight and Balance record that includes the same.
    5. Operating Handbooks and the Flight Manual Supplements relating to added or modified systems.
    6. Instructions for Continued Airworthiness (ICA) issued for routine checks and inspections, relating to aircraft changes.

    Today, most aircraft are monitored under a third-party maintenance program such as CAMP or Traxxall that will remind operators when inspections and checks are due, and will track service changes. However, bad data in means bad results.

    The equipment list that your maintenance tracker uses, must reflect the true status of the aircraft, including part and serial numbers. Changes that have taken place along the way must be fully reflected within the tracker’s database.

    Unfortunately, if you have acquired an aircraft that has the inherent error of miscued data, it is inevitably much harder to go back into the history and correct it.

    Do your due diligence during a pre-purchase, not only for the airframe and engines, but the avionics and all accessories. Remember that avionics includes cockpit, remote equipment and cabin systems.

    Obsolescence of Cockpit Displays

    One common area of obsolescence in avionics relates to the cockpit displays. These may look digital and somewhat modern, but on further investigation the buyer may find they are Cathode-Ray Tube (CRT) and are no longer fully-supported. There may even be a notification from the display manufacturer listing an end date of in-service support.

    Upgrading cockpit displays is a major, and extensive undertaking. Because current displays are larger and there are fewer of them, they can each present more information to the pilots. That means there will be numerous available options, where the inputs will vary.

    What you see is not always what you get, so make sure you know what can be selected by the pilots. Upgrading from CRT to flat panel is one large expense. Adding desired features to an already-modernized cockpit is another.

    An example of desirable options will be charts and maps. Others include lightning display, enhanced vision, synthetic vision, and the list goes on...

    Production Level of the Avionics Suite

    The different aircraft manufacturers have their own branding for the suites of cockpit systems they provide in modern aircraft. The overall suite may be the same, but it will have a different branding name for each of the aircraft for which it is selected to be the primary avionics.

    The aircraft manufacturer will outfit their aircraft with this special branded suite, and it will begin as version one. However, nothing stays the same. Eventually a version two will enter production as the same suite of avionics with the identical branding.

    Savvy buyers (or their consultants) will know that version two was introduced at aircraft ‘serial number X’, so they will know whether an aircraft of interest does or does not have the latest version.

    Sadly, some later production levels are offering both new features and compliance with recent mandates. For the buyer, this means, if you want to operate your purchased aircraft in a different airspace, or in a different operating role, you will need to meet the mandate. This implies upgrading the avionics to the later version.

    Because the primary avionics is pretty much everything, you can rightly surmise that changing from Version 1 to Version 2 could levy a large fee. Make sure you know exactly what aircraft and avionics you are trading up, or down, to.

    Avionics Ground Tests

    During a pre-purchase inspection, the avionics will be checked along with the airframe and engines. Keep an eye out for how the aircraft is opened-up. Sometimes the pre-purchase is undertaken along with a major inspection. If you have any avionics questions resulting from your review, this could be the ideal time to do an actual visual inspection.

    Visual inspections may be to check on part or serial numbers of remote equipment, or to check on a modification. Either way, access is always time-consuming and expensive, so leverage opportunities where they may present.

    Table A (above) provides most of the items that should be included for a ground check, and only some of them are function-related. One that is not is ‘database updates’ which are provided in different ways and involve a subscription of sorts. 

    You do not want a break in the subscription, so make sure there is some overlap during an aircraft changing hands.

    The method of updating databases varies, anywhere from using a CD, through USB, to portable updater. Most smart installations provide easy and accessible places to update onboard systems. Do not forget those in the cabin (such as Airshow).

    Some software updates require that electronic cards and equipment be returned to the factory or exchanged. Allow sufficient time for anything that needs to be shipped.

    Avionics Flight Tests

    Table A also provides a list of items for a flight test. Bearing in mind that the avionics is only one part of the aircraft, you can imagine just how many tests there should be to know how airworthy an aircraft truly is.

    ‘Airworthy’ is a safety-related term, but for transacting an aircraft, it extends to everything working as advertised. Many cockpit selections are more feature- than safety-related, but for a pilot they will be frustrating if they malfunction.

    • ‘Shake the aircraft down’ – at altitude, on a couple of approaches, and while executing a flight plan.
    • Pressurize the cabin, especially if any major work was recently completed.
    • Use a checklist, both for the airframe/engines and the avionics.
    • Do not short-change the avionics in favor of other systems, either because you see avionics as secondary, or you just don’t know what is important to check.

    Table A lists some of the avionics airborne tests, focusing on systems that can only be verified as operational by flying them.

    Regardless of a hangar systems function test, all the avionics should also be monitored in flight. By conducting a few approaches and getting to altitude, the pilots will be testing most systems by default, so it is not such an extra burden to complete.

    Cockpit Cosmetics

    How an aircraft is treated by its owner will be reflected in the appearance of its exterior, cabin and cockpit, with the latter receiving the lowest priority. Aircraft that have multiple owners, or are frequently used for charter have a greater risk of a cockpit cosmetics issue. For a pre-purchase inspection:

    • Look for bent or damaged knobs, switches and controls, where intermittency of function may occur.
    • Look, too, for grubby congested control panels that may have taken a few cups of coffee over the years. These could also be operating unreliably.
    • Displays should not be dim, displaying misleading colors, or showing artifacts due to shorted pixels.
    • The cockpit pedestal and side panels are prone to the most cosmetic damage because the pedestal gets trodden on and the side panels are used as storage areas. Pay close attention to aft pedestal and side located controllers for possible damage that may be greater than cosmetics.
    • Make sure all the placards for both airframe and avionics are present and legible.

    Service and Repair Programs

    Some operators take the risk and do without service programs. Others find it more useful to have predictability in annual service costs, including for avionics.

    Both the equipment and third-party service providers will offer avionics service programs. Essentially, you pay a fixed annual fee for the service and repair of most systems and a rated fee for additional service, not covered.

    Those aircraft maintained under such programs are more likely to have fully serviceable avionics and require less oversight for reliability.

    Two avionics programs from equipment manufacturers, for example, are Collins Aerospace’s CASP and Honeywell’s MSP (formally HAPP). Both have been around a long time, are reliable, and very popular. In addition, JSSI offers its Tip-to-Tail aircraft service program that includes avionics.

    If you acquire an aircraft that had a service program, you will need to transfer the ownership. And if the aircraft did not have a program previously, it may be wise to start one now.

    In Summary…

    The most important tip to take away from this article is not to underestimate the importance of a thorough avionics pre-purchase inspection when trading an aircraft. For both seller and buyer alike, delays and unexpected expenses are never welcome.

    The seller should properly prepare the aircraft for sale, and the buyer should properly inspect the aircraft, including a thorough review its records.

    When I was in the UK Fleet Air Arm – the air-wing of the Royal Navy – they termed me and my colleagues ‘Airy Fairies’. This was partially borne from a fear of the unknown: who were these mysterious types that can keep heaps of metal airborne?

    Worse still, as an avionics specialist on an aircraft carrier full of able seamen, I felt alien – not elitist, but different. All of this eventually translates across to how avionics always was a secondary, poorly understood aspect of the aircraft. Not anymore.

    Avionics is now the central nervous system, sensing, monitoring, and controlling just about everything that keeps the aircraft up in the air. So, when you review an aircraft for a transaction, pay close attention to its avionics.

    Do you have a specific aircraft maintenance, upgrade or repair need?

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