Conscientious airplane walk-arounds are never a waste of time
The pre-flight walk-around inspection of an aircraft, by the pilot or a trusted crew member is a time-honoured, vital facet of good airmanship. Generations of great pilots have always taken the time and trouble, in all weathers, to take a good look before taking off. The evocative expression, ‘kicking the tyres‘ (to listen for a different tone from one – indicating a possible discrepancy in tyre pressure) harks back to the ‘good old days’, when there was substantially less engine noise around tarmacs. In approximately 20,000 walk-arounds, over 55 years, only 3 paid a bountiful dividend – but the rest were never a waste of time.
This is the sixth article in a planned occasional series, sharing some most memorable and treasured experiences. This one is another from my own career : We do plan to feature other highly esteemed pilot friends and colleagues, who are only too willing to share their collective aviation experience. The crucial lessons that we learned along the way are just as valid today. They contribute, in no small way, to that intangible but essential quality known in aviation as ‘airmanship’.
- 1967 : The Auster
The first of my ‘big 3’ occurred in August 1967, when employed as a 20-yo junior flight instructor. I was tasked with flying a wonderful antique Auster J5L to a nearby country airfield and wait most of the day, while a 100-hour engineering inspection was carried out. Around 1600hrs, the engineers wheeled the airplane out of their maintenance hangar and handed me the new Maintenance Release. “Jump in”, said the chief maintenance engineer,“we’ll give you a swing on the propeller.” (The de Havilland Gypsy Major engine, fitted to the Auster, didn’t have a starter motor.)
“Hang on“, I replied, “I haven’t carried out a walk-around.” “Mate“, said the engineer, grinning smugly to his colleagues, “She’s just come out of the 100-hourly!“
I was thinking, ‘All the more reason’, but I returned, simply, “Thanks, but I have never yet flown an airplane without having first walked around it and I don’t intend to vary that policy, today“. “But there’s some nasty weather headed this way – hop in and we’ll get you going.“ I ignored this last entreaty, totally; it was 1600 hrs on a Friday afternoon and these guys simply wanted me gone, so they could have a beer, before heading off home. I surveyed the sky and there was some approaching low cloud and rain showers; my outbound track back home was reasonably clear and the showers were still about 20 minutes away.
I circumnavigated the airplane. I had witnessed it being pushed out of the hangar after a supposedly-thorough 100-hourly maintenance inspection. It should have been perfect – yet I discovered 2 unbelievable derelictions of care and responsibility:
- The right aileron cable was disconnected and was lying loose and visible, below the fabric-covered wingtip; and
- The engine oil cap was missing : An apprentice engineer was dispatched to the hangar and he located it on a workbench.
While these 2 blunders were being remedied, the other engineers had formed a small semi-circle and, like me, were awaiting their boss’s response to these serious lapses: There was no apology, no contrition, just, “Well, fellers, there’s a careful pilot for you!” I was dismayed and disgusted. I just strapped myself in; someone swung the propeller for me and I just taxied away and departed for home, trying hard to put it out of my mind.
Had I departed without completing that walk around, I would have undoubtedly had the character-building experience of a certain engine failure or seizure on or after take-off, followed by the twin challenges of executing a full forced landing with an oil-covered windscreen and partly functioning or, worse still, jammed aileron controls – in approaching bad weather.
My employer never again returned to that maintenance organisation, yet I was instructed not to submit an air safety incident report. I still regret not doing so. Their collective negligence could have proved fatal – to me.
2. 1984 : The DC-9-30
October 1984 found me completing my command upgrade to the beautiful DC-9-30. On a regular Melbourne to Hobart return flight – MEL-HBA-MEL – my training captain and I were on the turn-around, in Hobart. While executing a second walk-around inspection (following my initial one, completed in Melbourne prior to departure), I was circumnavigating anti-clockwise around the DC-9, dodging the usual collection of obstacles such as refuelling hoses and pump vehicles and heading for the left wheel well, when I noticed something ‘odd‘ sticking out at an odd angle, from the leading edge of the left main landing gear door section, fastened to the gear leg. The door edge was well-silhouetted against the clear sky and the view was foreign to my eyes. I moved closer, to investigate.
Almost simultaneously, our very conscientious ground licensed aircraft maintenance engineer -LAME – was homing in as well. We just looked at each other, as the reality dawned on us: the object projecting out from the door’s leading edge was an almost-separated 100mm/4-inch-long section of the stainless steel strip, fastened along one edge of its curved profile, that is pressed against and forms a seal with the underside of the wing, when the doors close during the landing gear retraction cycle. This particular section had fatigued from normal wear and tear and was hanging on only by a 1/4 inch/6mm ‘thread’. The engineer broke it off and I asked to keep it, as a souvenir.
For what we had both realised from the outset, was that on the next take-off – our departure from Hobart – or a subsequent one, that loose fragment was very likely to separate completely – and it was perfectly aligned with the intake of the left engine, mounted on the aft fuselage. On initial take-off rotation, with the main landing gear still on the ground and the engines much lower than usual – and a 135 kt/270km/hr air blast tearing at it, that little fragment could have totally destroyed the left engine and given this commander-under-training a very real-world ‘engine failure/fire/severe damage’ situation to deal with, instead of a routine simulator training exercise.
That fragment has resided on the wall of my study, ever since.
3. 2002 : The B737-800
My First Officer and I had already flown from Melbourne to Brisbane, to crew a further night B737-800 service – in a different airplane – to overnight in Cairns, in far North Queensland (FNQ). I was waiting on the tarmac, as our second aircraft taxyed in and shut-down, at 2030hrs AEST.
As soon as the rotating beacons were extinguished, I commenced my walk-around inspection under the tarmac lighting, proceeding anti-clockwise around the airplane from the nose, as was my habit, differing from the published clockwise recommendation. (It always made more sense to me to proceed anti-clockwise, as the light switch for the main landing gear (MLG) wheel wells was located on the left-hand side and, at night, could provide the necessary illumination at the earliest opportunity. Even armed with a torch, the full illumination was very helpful.)
The B737 doesn’t have doors to enclose the wheel wells when the MLG is retracted, only small doors fitted to the MLG legs : the MLG wheels and tyres, themselves, form the wheel well seal, following retraction. Ground access into the wheel wells is relatively simple, if a little challenging, to avoid the black tyre rubber ‘skid marks‘ on one’s uniform shirt, resulting from brushing up against the rubber sealing panels for the tyres, that line the circular wheel-well opening.
The space inside the main gear wheel well is subdivided, longitudinally by the substantial ‘keel beam‘, which, as in a boat or ship, forms the basis of the longitudinal strength of the entire structure, much like a spine. Measuring some 300mm/12 inches wide, at this point, its flat top surface serves as a platform to support a number of component parts, such as hydraulic lines, electrical cable runs and some various other small component assemblies. It looks a bit cluttered but after many years and many walk-arounds, it had for me the familiar look of an untidy desk; ‘it could be tidier but, at least, I do know where everything is‘, I was thinking. But amongst the familiar clutter, something seemed different.
I took a second look around the L wheel-well, without satisfying my initial curiosity and exited back out, to continue my walk around the left wing and engine. ‘I’d take a fresh look, when I reached the other wheel well on the right side’, I figured. After checking the tail and right wing and engine, I ducked under the wing centre section and stood fully upright again, taking in the space from the opposite side. Again, everything seemed familiar and intact – no leaks – nothing out of place – until …
I looked closely at the central keel beam, again. My initial thought was confirmed: there was something different – a small can, something like the size, shape and silver colour of an airline-sized can of ‘Diet-Coke‘, but not that, resting happily on the keel beam. On top of it, lay a 1/2in drive socket open-ended spanner head and a thread of steel wire protruded from a small aperture, beneath the spanner. The canister, itself, was sitting against one of the hydraulic line runs that was acting as a ‘safety railing’, about 30mm/1.5in, above the keel beam. Otherwise, it was totally unrestrained to the left, forward, aft and vertically. In other words, loose. I realised that it had been in its present location when the airplane landed, just before 2030hrs, as no other person had been near the wheel wells, except me. I picked up the intruder, spanner included and the weight impressed me, for such a relatively small item. It was a virtually full canister of 0.0030 inch stainless steel locking wire, used by engineers to secure nuts and other assemblies.
I exited the wheel well again, just as a ground maintenance engineer approached. “Oh, thanks“, he said, offering to relieve me of it; “We’ve been looking for that!”
“No“, I replied, “This is mine, for now – where is your tarmac foreman’s office located?” He indicated. I walked over and into the office, holding up the canister and the spanner head, in each hand.
“Oh thanks, Captain“, said the tarmac foreman, as I handed them to him. “We’ve been looking for those two items, since midnight, last night – they were not accounted for : Where did you find them?” “On the keel beam of the -800 over on Gate 23, when I was completing my walk-around“, I replied. “Didn’t that airplane just arrive – from Cairns?” “Yes“, I said. He consulted the airplane’s movements for the day, on his computer. “Then” he said, looking quite shocked, “those bits have been sitting on that keel beam ever since midnight, last night – for over 20 hours. The airplane has done 4 return trips to FNQ, so far today. Somehow, they haven’t fallen out, or been jolted out on landing and not one crew member or ground engineer has noticed them, until now.”
I was already thinking of just some of the many variations of possibilities that could have ensued, during the 8 previous flight, such as:
- The maelstrom of airflow around the open wheel wells, on any of the 8 take-offs or landings conducted before I noticed those foreign objects, could have dragged increasing lengths of the lock wire out of the canister, forming a ‘spider’s web‘ of stainless steel lock wire which, on landing gear retraction or extension, could have wreaked havoc on any of the hundreds of innocent and unsuspecting electrical and hydraulic components, anywhere in that wheel well; it would undoubtedly led to a very difficult situation for the operating crew, trying to troubleshoot, sifting through a litany of false warnings as well as real ones.
- Either the spanner head, or the canister itself, could have been jolted or simply fallen out, as the airplane manoeuvred after takeoff or, especially, on approach to landing, over the cities of Brisbane or Cairns. As weighty projectiles, they could have easily killed someone, or crashed through a building window or vehicle windscreen.
- Either item, or both, could have fallen out onto a tarmac, taxiway or runway and caused a foreign object hazard for the engines or tyres of the next-passing airplane : Remember the fatal Concorde tragedy?
On this occasion, after conferring with the Company Flight Safety Manager, I did submit an Aviation Safety Incident Report (ASIR) on this significant lapse in standard maintenance procedures. Nevertheless, I did have some nightmares about the various possibilities, for some time, in the months that followed.
The major lesson I learned from these 3 incidents, roughly 20 years apart over those years, was that no matter what time constraints may be present, the simple walk-around inspection is non-negotiable and must be conscientious, even if you end up finding nothing wrong. 3 problems, in 55 years and approximately 20,000 walk-arounds, is a very low score; but it is still 3 more than it should have been. They underscore the overwhelming need for standard operating procedures (SOPs) to be followed by all who commit – and support aviation, in all its facets.
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