The Annual Inspection: one inspection per year, or one year per inspection?

In theory, an annual inspection is maintenance performed once a year, not maintenance that takes a year to perform. For some of us fledgling mechanics though, the latter sounds more accurate when faced with an unfamiliar aircraft that’s been flying for a whole lot longer than you’ve been working on planes! North Aero’s 1948 Luscombe is a relatively small aircraft, but when you pull out the floorboards and start digging into the cables and wiring that keep its little wings moving ever upwards, the aircraft grows exponentially and the concept of inspecting the airframe grows more and more daunting.


Aviation maintenance school teaches you to “read the manual,” but they don’t tell you what to do when the manual is a compilation of contradictory magazine articles detailing arguments between a bunch of random Luscombe owners from the 1950s who all had their own individual opinion on how the plane should be flown and maintained. School teaches you how to torque bolts and tension control cables, but it teaches you numbers, not the meaning of vague statements such as “control cables should be adjusted until they are just ‘snug’.” That was the only information we could find on tensioning Luscombe control cables, and it wasn’t even in the maintenance manual; we dug that gem out of a random service bulletin from 1951!

In Airframe class, you learned about hydraulic brake systems, and maybe your instructor made a passing comment about mechanical brakes, but most likely it was something along the lines of “airplanes used to have mechanical brakes but they don’t anymore.” And then you meet an aircraft from essentially WWII and find out that some aircraft do in fact still have mechanical brakes! So you jump down the rabbit hole and tightrope walk your way along the 1/16” cable connecting your brake pedals to the drum brakes, noticing the startling similarity between these little cables and the ones that run from the handles of your  bicycle to the brakes on those tires… And you realize that all those times you hit the brakes when landing the little Luscombe that the slight give you felt was the cables stretching… 


The phenolic brake pulleys that were originally installed in the Luscombe are know to break (no pun intended) under too much pressure. We replaced them with metal pulleys that don't suffer from that issue.

These are just a few of the exciting and daunting adventures we took on when we began what we thought was going to be a relatively simple and straightforward annual inspection on a plane that weighs less than a thousand pounds and would fit in most average garages. Over the course of a three and a half month period, the maintenance crew at North Aero pulled little Luscombe N1302B apart and then slowly reassembled it, fixing discrepancies at every chance we got along the way. There are many different levels of maintenance that be achieved by a shop, and in theory the Luscombe was pretty safe to be flying before its annual inspection, but it’s definitely eye opening experience to dig into the guts of an airplane find out just how many little bolts and nuts are out of specification, and how many bits of hardware aren’t really the right parts at all. While in some cases it might take a lot to make an aircraft truly unsafe, it takes very little to make an aircraft unworthy. One missing logbook entry or one screw thread too few poking out the end of a nut, and an aircraft can be deemed unairworthy and not fit to fly until the issue is addressed. As the Luscombe annual came to a close, and we reached the end of our extensive squawk list, we felt secure in the knowledge that the Luscombe is not only safer, but also more legal to be flown!


Look at those tiny little cables! The 1/16" thick brake cables previously installed on the Luscombe would stretch a little each time you stepped on the brakes.


The drum brakes on the Luscombe are a blast to the past, a relic of the early 1900s and similar to something you might find on an original VW bug. Nowadays, these aircraft have been recertified to use hydraulic brake systems that can replace the old mechanical drum brakes.

If you take a lesson in the Luscombe now, you might notice the beefier brake cables running down to those funny little drum brakes, or the new radio and intercom wiring that doesn’t deafen you with static when you add full power on a go-around from a bouncy landing. You might notice before your flight that the tires are new and unworn, and we hope you try your best on your lesson to keep them from developing the bald spots that did in the last tires it had! The carb heat cable should feel smooth and easy to operate, and definitely shouldn’t come out of the panel in your hand as you operate it, a refreshing change from the sticky situation we found when we started to examine the aircraft. You shouldn’t feel fuel leaking out of the fuel selector when you reach down to switch the tanks, and please take a moment to appreciate that the fuel selectors point correctly to the labeled “on” and “off” positions so that you're not guessing at which way you should turn the handle. You might not see all the small pieces of hardware that we replaced, but rest assured that the bolts and nuts holding the little plane together now actually match the drawings in the maintenance manuals.


So book your flight in the Luscombe today, check out the new and improved features it has to offer, get a taste of what it feels like to fly an aircraft that came off the production line 75 years ago, and be thankful you’re not the one tasked with completing its maintenance inspections!


Sophia is a licensed mechanic as well as private and instrument rated pilot, currently turning wrenches and writing blog posts to make ends meet until she logs enough hours in the left seat to start making the big bucks as a corporate pilot. Her hobbies include flying and working on airplanes, and at any hour of any day she is most likely to be found in the North Aero hangar or somewhere else around the Salinas Airport.

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