Flight Control Systems — Page 169, Lesson 219

Let’s pick this up right where the inspection process gets practical. We’re now into the detailed requirements for inspecting flight control systems after assembly, and this is where the paperwork and the physical checks come together. First, there’s a real-world problem the regulations address. After the aircraft is fully assembled, you simply cannot see every part of the control system anymore. Some sections get progressively ‘boxed in’ and sealed during assembly — meaning they’re covered up and closed off as the build proceeds. So the rule is this: before any section that is liable to be sealed gets sealed, you must establish the condition and security of that section to the satisfaction of the persons named in paragraph 5 — we’ll get to who those people are in a moment. And you must endorse the related Inspection Record accordingly. In other words, you sign off that the hidden part was checked and is good before you bury it. Next, the Inspection Records themselves. They must be carefully prepared so that any duplicate inspection required at an early stage during assembly is clearly indicated. Why does that matter? Because if you flag it early, you avoid unnecessary dismantling later. You don’t want to take the aircraft apart again just to re-check something that should have been caught at the right moment in the build sequence. Now, the heart of it — paragraph 4.4. The correct functioning of control systems is, at all times, of vital importance to airworthiness. That’s the governing principle. So the people doing this work — suitably licensed aircraft engineers and members of approved inspection organisations responsible for the inspection or duplicate inspection — must be thoroughly conversant with the systems concerned. They have to know these systems inside out. And the inspection itself must be carried out systematically, to ensure that each and every part of the system is correctly assembled, and is able to operate freely over the specified range of movement without the risk of fouling. Fouling means something snagging or rubbing where it shouldn’t. Also, it must be correctly and adequately locked, clean, and correctly lubricated. And finally — this is a subtle but critical point — it must be working in the correct sense in relation to the movement of the control by the crew. That means the control surface must move in the direction the pilot’s input would logically produce. Pull back on the column, the elevator goes up — that’s the correct sense. If it went the wrong way, you’d have a catastrophic situation. Now, who is authorised to certify these duplicate inspections? This is paragraph 5, and it references BCAR Section A Chapter A6-2. The first and second parts of the duplicate inspection can be made by two groups. First, aircraft engineers appropriately licensed in Categories A, B, C, and D. Second, members of appropriately Approved Organisations who are considered by the Chief Inspector competent to make such inspections, in accordance with Airworthiness Notice No. 3. But there’s an important exception for minor adjustments. When the aircraft is away from base, the second part of the duplicate inspection may be performed by a pilot or flight engineer licensed for the type of aircraft concerned. So the first inspection is done by the engineer, and the second part — the independent check — can be done by a qualified pilot or flight engineer when you’re out in the field and no second engineer is available. Finally, the certification itself. The recommended form for certifying the duplicate inspection is a statement: “Duplicate inspection performed in accordance with the requirements of BCAR, Section A Chapter A6-2.” Then you have two signature blocks — one for the 1st Inspection and one for the 2nd Inspection — each with a signature and an authority line, plus the date. That’s the formal record that both independent checks were done and signed off by the right people. So the whole picture is: inspect everything systematically, seal nothing until it’s verified, record it clearly, and have two qualified people independently certify it — with the pilot or flight engineer allowed to step in for the second check on minor adjustments away from base.