Ensayos de compresión plana

A flight is deemed to have terminated once an aircraft comes to rest at the end of the flight (CAANZ, 2015a) which, for an airline, will be arrival at the terminal gate. From this point on, provided the aircraft is to be utilised on another flight, the process of readying the aircraft for the next sector begins. The turn-around process includes a number of planned activities undertaken by various operational groups. Figure 2.2 depicts the typical passenger handling and aircraft servicing activities which must be accomplished, often within a short space of time.

Figure 2.2Passenger handling and aircraft servicing activities for a 35 minute turnaround on a domestically operated B737 (source: Wu, 2008).Note: C.C. checks refers to cabin crew checks of the aircraft cabin.

Within the turnaround time, certain maintenance activities are also undertaken. Line maintenance personnel11_{will enter the cockpit and check the aircraft technical log (see 2.6,}

below) for any defects written up by the inbound flight crew. It is at this point that the aircraft engineer may have an opportunity to speak with the pilots about any maintenance issues concerning the aircraft. Whether this occurs, however, is dependent upon the movements of the flight crew who may have vacated the cockpit prior to the aircraft engineer arriving. This is by no mean an unusual occurrence for several reasons:

ƒ The turn-around process may involve a scheduled crew swap whereby the flight crew must change aircraft for their next sector. The crew may have to travel some distance to get themselves to another gate in a short space of time.

ƒ The sector may have been the last rostered flight for the crew that day. Crew transport schedules, post flight administration and fatigue following a long duty may induce pilots to vacate the aircraft expeditiously.

ƒ Mid-duty respite. Depending on the length of time the aircraft is scheduled to be at the gate, the crew may utilise the opportunity a turnaround provides for bathroom and refreshment breaks.

ƒ Flight crew turnaround duties. Specific turnaround activities, such as performing an aircraft pre-flight inspection (see 2.5.2) may take the crew away from the flight deck.

Aside from an aircraft engineer being alerted to a maintenance issue either by a review of the technical log or by the pilots themselves, there are two other opportunities which allow for the discovery of any maintenance issues prior to the aircraft’s next flight. Before it departs on its next sector, the aircraft is subject to two inspections; one conducted by an aircraft engineer and the other by a member of the flight crew.

2.5.1 A Typical Transit Check

Even a short turnaround time affords an opportunity for the aircraft to be checked prior to its next flight. While the aircraft is parked at the gate, a line maintenance engineer will conduct an external examination of certain flight safety-critical systems and components. This is known as a transit check. While the actual items will vary somewhat, the typical elements are those which are easily accessible to the engineer in the time available (Figure 2.3). Should a defect be discovered during the line maintenance transit check, the aircraft engineer will liaise with the Maintenance Control centre as to what course of action will be taken. Whether an effort is made to repair the defect while the aircraft is at the gate depends upon the airline’s flight schedule as well as the nature of the defect itself.

x Service engine oil if required

x Check ram air inlet/exhaust doors and cabin outflow valve for condition and obstructions

x Check positive pressure relief valves for indication that valves have opened x Check moveable flight control surfaces for condition, obstructions, and locks x Make sure that the fuelling station door is closed

x Check nose and main landing gear tyres and wheels for obvious damage x Check navigation and communication antennas for condition

x Check static ports, TAT probe, pitot static probes, and AOA vanes for condition x Check crew oxygen discharge disc

x Check drain mast areas and drains for leakage of fuel and/or hydraulic fluid x Check vertical fin and rudder, horizontal stabilisers and elevators for damage,

evidence of fuel leaks

x Check for missing or damaged static dischargers

x Check lower wing surfaces and wing tips for damage and fuel leakage

x Check engine cowlings for obvious damage, check blowout door in not open and latches are secure

x Check inlet cowl, fan rotor spinner, and fan rotor blades on both engines

Figure 2.3Typical transit check for a twin engine jet (source Kinnison & Siddiqui, 2013)

2.5.2 Flight Crew Walk-Around Check

In addition to the inspection undertaken by line maintenance, the crew who will operate the aircraft on its next sector must also conduct their own check. CAR Part 91.201 Safety of Aircraft states that prior to operating, the pilot-in-command of an aircraft must be satisfied that the aircraft has been inspected and that it is in an airworthy and safe condition for flight (CAANZ, 2015b). The particulars of what a pilot must check for during his/her inspection are specific to the type of aircraft which is operated. The details are published by the aircraft manufacturer and are contained in the aircraft’s operating manual. However, many of the items checked will be the same as those inspected during the line maintenance transit check. An airline’s operating procedures will specify whether the pre-flight inspection is undertaken by the captain or the first/second officer or whether it is a function which is attached to a particular role i.e. Pilot Flying (PF) or Pilot Monitoring (PM). A typical pre-flight inspection

is carried out by walking around the aircraft in a systematic manner whilst visually checking the integrity of the specified aircraft components (Figure 2.4).

Figure 2.4Pre-flight inspection walk-around flow

If a defect is discovered by a pilot during the walk-around check, consultation with a line maintenance engineer will be required. If an engineer cannot be located at the aircraft, the crew will use the applicable radio communication channel to request that an engineer attend the aircraft. The pilot(s) and engineer(s) will then discuss the defect, the associated impact it could have on the operation of the aircraft and the appropriate entry to be made into the aircraft’s logbook.