BY David Villiers
Chair Airworthiness Panel
PHOTOS: From 'The Daily Inspection', a series of videos produced by Justin Couch at Southern Cross GC.
You can view them all and lots more on the GA Youtube channel
tinyurl.com/GA-channel
The airworthiness of our gliders is assured through a multi-layered system that starts with the aircraft’s design and extends through certification, manufacture, maintenance and operation. In this system some elements seem very remote from the day-to-day operations of the aircraft, others are more immediate. The part which we all engage with most frequently is the Daily Inspection (DI), which is our last line of defence against launching in an unairworthy aircraft.
Obviously, then, this is a critical aspect of airworthiness management, and the one thing that every solo pilot will undertake on a regular basis. As the last line of defence, the DI needs above all to be effective, and in this sense ‘effective’ means that there is a high probability that the inspection will find airworthiness problems.
However, experience has shown that DIs are not always effective, and there are numerous examples of aircraft being flown with defects which should have been found by the DI. These range from the less serious (ie, dirty canopies, dirt and assorted detritus is the cockpit, broken undercarriage door bungees, missing or illegible placards) to very serious threats to safety (disconnected controls, unsafe l’hotellier fittings, structural damage to the airframe and wildlife stowaways).
The reasons behind these failures are varied, but rarely new. Threat and error management is an integral part of airworthiness control. Most of the issues that can result in a defect being missed during a DI are generally well known, but unfortunately, many of those issues can by put down to the fact that DIs are carried out by humans, and all humans are fallible.
Complacency
Daily inspections are a task that we carry out frequently and, regrettably, almost mechanically. We do the same things, the same way, in the same order, looking in the same places for the same things. All too often, we’re doing this on the same aircraft, be it a club trainer or a club or privately owned single seater. This is how people work and we need to recognise that. By understanding this fact, we can reduce the threat simply by being conscientiously thorough, even when inspecting an aircraft for the hundredth time. The fact that you’ve inspected an aircraft many times before does not reduce the risk of a defect popping up unexpectedly.
A closely related threat is Confirmation Bias. This is when an inspector sees what he or she expects to see. An example is checking l’hotellier fittings. Just because there is a pin through the fitting does not mean that it is in the correct hole. There have been examples of pins being fitted into l’hotellier fittings in positions that do not lock the fitting. Another example is checking that the main pin is installed but not noticing that its locking mechanism has not been properly engaged.
Access and Visibility
Many spots inside a sailplane can be very difficult to access, where the ability to see is impaired by structure, glare (for instance, peering into a dark compartment surrounded by white structure in bright sunlight) or simply poor access. Similarly, there are places where getting a hand in to feel for correct connections can be very difficult. In these cases, the solution can be as simple as providing shade or using tools such as a flashlight and mirror-on-a-stick.
Alternatively, touch can be employed instead of sight, and vice-versa. However, in a few places such substitution can bring its own threats. An example is checking the locking of a Polish connector as found on Jantars and PW6s. Feeling for the correct engagement of the locking pin has been known to unlock the pin – in these cases, sight is a better inspection method and may well require using a flashlight and mirror.
Tools, Facilities and Documentation
Sometimes, when tools are unavailable, pilots feel innate pressure to proceed without them, similar to facilities. No one likes rolling around on a cold or stony surface to inspect the undercarriage. Having your own tools is a great way to overcome this threat, but little can be done about the cold, stony ground except to dress accordingly, even if it means getting changed before take-off.
Checking tyre pressure is another job that requires tooling – a pressure gauge, maybe a valve extension and a pump or compressor. Few club members carry these tools, so if they cannot be accessed quickly and easily, the temptation is to skip the task. A poorly inflated tyre can quickly turn into a problem given the right (wrong?) circumstances.
Documentation is also an issue. The Flight Manuals of many types of glider list items that must be inspected at each DI. So, ready access to the Flight Manual is required, particularly if the inspector is new to the aircraft.
Finally, a simple tip is access to a pen to sign the Maintenance Release. How often do we have to search for a pen, and how often have pens been found loose in the cockpit?
Stress
We face many types of stress, and all can have a deleterious effect on the conduct of a Daily Inspector. Fatigue is particularly insidious, as is dehydration. Heat and humidity can also raise stress levels. The impact of these can lead to an internally driven pressure to get the job over with, resulting in cut corners and raised risk of missing something important. Also, do not underestimate the effects of mood on performance. An angry or upset inspector also runs a heightened risk of missing something.
Such stresses can be internally or externally driven. Conflict, personal circumstances, family and life episodes can all contribute to stress. Recognising the impact that stress can have on DI performance will help overcome these issues, but it may be better to get someone else to do the inspection. If you are is too stressed to do an effective DI, the wisdom of flying should also be questioned.
Time Pressure
Time is always a consideration in conducting a DI. Whether it be to assure a desired place in the launch queue, to make the best of soaring conditions, or simply to get the operation moving, hurrying an inspection is never a good idea. Rushing flight preparations can have effects well beyond the DI, such as poor flight and task preparation. The solution is often just a little planning. Leaving time to do a thorough DI and prepare the aircraft (and pilot) can significantly reduce stress and lower the risk of missing a defect during the DI.
Interruptions and Distractions
Distractions and interruptions are a continual threat to the completion of an effective DI. Everyone has been interrupted during a DI, and everyone has interrupted someone else, but this is easily fixed. Just be aware of the impact of an interruption and try not to do it. Often, the interruption can be as simple as asking someone to puff in a pitot tube, but whatever the reason, it is still an interruption.
Annual Inspectors are often also interrupted by someone wanting their advice about an airworthiness issue of another aircraft, but Annual Inspectors are not immune to the effects of being interrupted. Consider the person being interrupted and their task before you approach them for assistance. We are careful not to interrupt or distract a pilot during their CHAOTIC check; we should apply the same discipline to someone doing a DI.
Distractions are another issue. Something is always going on that can take an inspector’s attention away from the task at hand. As an inspector there is not much that you can do to avoid distractions, but try to remain focussed on your task.
Normalising Defects
Normalising defects refers to the human tendency to mentally accept a less than perfect situation because it doesn’t seem be a threat. Accepting a reduced tyre pressure because “it’ll be right” or “it’s been like that for weeks” is normalising the defect. The manufacturer specified the tyre pressure for a reason, and while the aircraft may operate normally with the lower pressure, in an out landing or a hard landing the lower pressure can contribute to a significantly higher risk of damage or injury.
This tendency to accept defects is most often seen on parts which degrade slowly (harness wear, placard legibility, control free play, tyre pressure) and the problem here is that the gradual degradation is not picked up by the inspector because they are used to seeing, and accepting, the defect, not realising that it has degraded to a level where it is now a safety threat.
Conclusion
An effective daily inspection is our last line of defence against flying an unairworthy aircraft, and one that we carry out almost automatically. We need to be aware of the criticality of the daily inspection, and the things that militate against an effective inspection. The GAus Daily Inspector’s Handbook, AIRW-M03, provides a great deal of guidance on doing an effective DI, and in Chapter 6 has a section on the sorts of threats and errors encountered when doing a daily inspection. It would behove all of us to reread this document periodically, particularly the sections on threat and error management.
