Pilot Error

Short finals, everything in the green … then the unexplained happened, that one per cent sheer terror which sometimes pops up among that 99 per cent sheer pleasure.

“A funny sort of flare,” was the comment from onlookers as the little tail-dragger bounced once, twice, then again with increasing severity, crow-hopping violently down the runway in brilliant sunshine.

The pilot was obviously in trouble. Bounce followed bounce in tragic undulation until the little Super Cub’s nose pointed right and engine noise indicated clearly that ground was the aim.

No good; the tiny aircraft was obviously uncontrollable.

The final crash came with typical suddenness near the airport boundary.

The first wisp of smoke blossomed into raw flame even as the fire trucks went careening across the airfield, sirens wailing an urgent dirge.

When it was all over, the last smouldering piece of wreckage extinguished the sorry task of finding out “why?” began.

The pilot was dead His passenger was seriously injured. The Super Cub was a mass of un-rebuildable metal and struts.

What sort of pilot was the dead man? According to the records, he had logged several hundred hours in trikes, but only about five in tail-wheel aircraft. And the last time he’d flown a tail-dragger was about two years previously, apart from a number of take-offs and landings with an instructor immediately before he began his last flight.

A thorough check of the wreckage proved there was nothing wrong with either airframe or engine before the last plunge.

One thing was very wrong, however, in the settings on board the Super Cub. Investigators found the adjustable stabiliser was set to the fully nose-down position.

Nett’s result of the investigators’ findings was a heartbreak.

The little aircraft could have made a safe go-round, however, belated, if only the pilot had re-trimmed the tail-dragger from an approach trim to go a go-round trim setting.

A go-round with the Super Cub trimmed for an approach would have exerted very high stick forces for the pilot – all the more disconcerting because of his low time on tailwheel types. Safety Board officials didn’t pull any punches. Their verdict was clearly a pilot error:

• The severe bouncing observed during the landing clearly indicated that the pilot did not perform the landing flare manoeuvre properly.

• The take-offs and landings made earlier with an instructor before that final flight was inadequate familiarisation, and didn’t prepare him sufficiently to take charge of the PA-18.

• Lack of skill in tail-wheel operations was further evidenced by the pilot’s delay in initiating a go-round.

Taking into account the fact that the total rate of accidents in tail-draggers is twice that of trikes, the Board reiterated the stark fact that wheelies, cross-wind operations, recovery from bounced landings and other factors make it imperative that the pilot flying a tail-dragger MUST show a high level of this peculiar proficiency before attempting flying operations.

Take a look at your own logbook. When did you last fly a tail-dragger (if you have the endorsement)?

More importantly, when do you next intend to fly one?

We suggest you read this article thoroughly, digest the fact that one man died, his passenger rendered useless for some time to come because of serious injuries, and a perfectly good aircraft was reduced to scrap metal, and then remember all this tragedy could have been avoided …

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The next incident in this article is hardly a pilot error, but it could happen to anyone. People could die horribly, and aircraft be irreparably bent, because of what happened to this particular Queen Air:

The August day was kind; the sun shone, and everything appeared right with the world of the Queen Air’s crew as they climbed into the Beech 65-80, ready for a charter trip.

Runup and take-off were normal. No snags and the Queen Air was set for a cruise climb to operating height.

There was no hint of pending trouble as the powerful twin climbed away steadily southbound – until the altimeter was nudging 20,000 feet.

Then it happened – trouble …

The skipper sniffed, sniffed again, then looked at his copilot who was wrinkling his nose at the unfamiliar electrical odour creeping cat-footed into the cockpit.

They both instinctively looked down at the floor-mounted circuit breakers. White smoke was curling out from somewhere near there into the cockpit.

“Mayday, Mayday …” The emergency was voiced almost at the same time as an emergency descent pattern was dialled in.

The smoke and smell persisted all the way down, but the Queen Air squeaked in without incident at the nearest major airfield. Both front-seat occupants had hazarded guesses at the source of that smoke and smell en route to the emergency airfield, but it wasn’t until the cockpit floor was ripped up and panels removed that the damage became apparent:

• Both voltage regulators and both alternator-rectifiers were u/s.

• The overboard nickel-cadmium battery was venting gas

• There was obvious fire damage on the voltage regulators and associated wire bundles under the cockpit floor between the pilots’ seats.

• Both alternator field windings were burnt and shorted.

• Both of the mainline circuit breakers and the adjacent landing gear circuit breaker were mechanically damaged.

• Both of the alternator field circuit breakers were also damaged. This was apparently the source of a chain reaction that had caused most of the damage.

The housing of one circuit-breaker was partially separated from the metal retaining cap, which allowed dust and other debris to collect inside the housing in the contact point area.

There was arcing within the breaker housing across the dust and muck at the contact points, which welded both sets of contact points closed.

This had obviously closed the circuit and left the field without circuit-breaker protection.

The damaged and inoperable floor-mounted circuit breakers had thus failed to give protection to the electrical system, which resulted in damage to the DC alternator system ·and an electrical fire.

A smart piece of electrical engineering deduction; but how did the alternator field circuit-breakers and mainline circuit-breakers get damaged in the first place?

The short, simple answer was that someone had stood on them.

Despite a Service Bulletin issued as far back as 1967, recommending the relocation of circuit-breakers to a less vulnerable position, this had not been done on this particular Queen Air …

The Beechcraft Shop Manual recommends that the circuit-breakers be inspected for looseness and proper operation during 1GO-hourlies on the pilots’ compartment.

Could this have happened to YOU?

* * *

The last incident in this issue of Pilot Error isn’t really a pilot error, but points quite clearly to proper inspections and checks by other people connected with the skipper.

A Piper Navajo Chieftain, operating a commuter airlines flight one September morning, was readied for departure in the standard manner.

The skipper did all his pre-flights in the accepted manner, climbed aboard and eventually started the engines.

A stickler for doing the right thing (a blessing, it turned out), he released brakes, taxied forward a short distance, and then carried out a brake check.

At least, it started that way …

As he applied brakes, the nose wheel failed and then cocked against the gear fork assembly.

The first thing the malfunction did was to damage the gear retract mechanism. Ultimately, the whole nose gear assembly collapsed.

What went wrong here?

Investigation revealed that the nose wheel, Cleveland P/N 40-768, to be precise, had failed and collapsed in fatigue.

The fatigue started from more than one place near the holes of three bolts that hold the rim to the wheel.

The fatigue area covered about half the fracture surface and ran out circumferentially from the multiple sources. Embarrassing? It could have been fatal if the pilot hadn’t stuck rigidly to his pre-taxi checks.

The strange thing was that the nose wheel had been taken apart and visually inspected less than nine hours before failure …

Investigators dug back into the records for similar incidents. They found that 36 cracked or failed nose wheel assemblies had been reported over the last five years.

Six of the reported cases had involved Cleveland P/N 40-120A wheels installed in Piper PA-31T model aircraft, the rest involving Cleveland P/N40-768 wheels fitted to various models in the Piper PA-31 Series.

Are You Too Old to Fly?

The question of how old one has to be before one stops flying is a hardy annual. The question in Australia remains virtually academic …

In the US, however, serious study has been given to the top age limit for flying.

Alas for the older pilots, rich in experience and deeply steeped in the eternal love of flying, researchers have found among American-licensed pilots that significant medical problems exist for pilots over 60, in the air charter/commuter game.

Taking aviation safety and protection of the travelling public as a yardstick, probing checks of personnel flying for three leading US air taxi/commuter operators have disclosed several vital failings or potential failings among the older pilots:

• Although studies to assess the effects of ageing on human performance have generally been inconclusive, the progressive degeneration of certain important physiological functions in humans is important to aviation safety, according to the investigators’ preamble.

• Cardiovascular disease, metabolic disease and central nervous system disorders are all items relating to the older pilot.

• These conditions relate to the ability of a pilot to resist fatigue, to adapt to rapidly changing environmental conditions and to perform under stress.

The findings are so important that the US National Transportation Safety Board have recommended a 60-yearsold top limit as an interim measure, to pilots flying air taxi/commuter operations.

An original regulation back in 1959 had already restricted pilots over 60 from flying air carrier operations.

The justification of recommending the interim measure against air taxi/commuter pilots includes the growing scale of the air taxi/commuter industry in recent years.

The nature of air taxi/commuter operations usually includes shorter flight segments, numerous approaches, landings and take-offs plus relatively low altitudes which subject the flights to more weather-related problems, means that the day of an air taxi/commuter pilot may be even greater than air carrier pilots.