16 September 2013

Sunrise, Sunset

My Office in 2008
I spent an evening with the air force fraternity on September 7, meeting up with serving friends and surviving foes alike, at the 50 Years Anniversary of the Alouette Helicopter Reunion. The Heli Reunion is an annual affair to preserve the fellowship between those serving in the air force and friends who have left for civilian life and other pastures, not always greener for the leaving.

I was quite happy to meet up with my personal Alouette instructor, Lt Col Syed, with whom as always, I spent many wasted moments chuckling over lame jokes that could only be shared in this peculiar relationship. He is now in a non-flying appointment, and we made small talk while waiting for the time to adjourn from the Air Movements Section in KL Base after the photo opportunity session to the Officers Mess yonder for dinner. We gazed endearingly at the three helicopters forming the backdrop for the photo op on the dispersal: the Nuri on the left, Alouette smack centre and EC725 on the right. The Nuri captured us. Col Syed wagered that rusty as we were, we could both strap in right there and then, start-up and rotor engage and take everyone on a city view sortie. Yes, the Nuri stirs nostalgia not just with her crew but with all who encounter her face to face.
A Nuri in a low-level fly by
People curious over my previous life in the military ask about what my daily routine was in the Nuri squadrons. There is no typical routine when we are driven by operational tasks. But what does pose as close to routine as it possibly can is a day on SAR standby.

On any typical day in a Nuri squadron, work starts with the ground-running of the Search And Rescue Standby aircraft, to ensure the squadron's commitment to National Search and Rescue is fulfilled alongside the SAR standby for fighter squadrons on training duties, and their occasional operational sorties.
The first on the scene, about 45 minutes before sunrise, are typically, the crewman, followed very shortly after, by the copilot. This is the routine manner in which the triple-redundancy in preflight checks along the hierarchy of the crew complement is fulfilled. Diligent copilots would arrive extra early and place a fresh operational authorisation sheet on the ops room console, and fill in the authorisation column with the date, the airframe number and aircraft type, the callsign, the captain's name, his own and the crewman's too, the task description and expected duration of the task under the various column headings as appropriate. The copilot and crewman then, often together, walk down first to the engineering flight line office to examine the BAT Book 3053 (Borang Angkatan Tentera or crudely translated as Armed Forces Form), or technical log book to ensure that the various engineering sub-tradesmen have checked and signed for their scope of duties on the aircraft concerned, that the aircraft has been fuelled for the standby task (approximately 4 hours 30 minutes fuel endurance) and that these are all on the correct date and time. Then they saunter to the aircraft and carry out the preflight checks in overlap. Eventually, and about half an hour before SAR standby duties commence, the aircraft captain arrives to sign the authorisation sheet, checks the BAT book, signs responsibility for the aircraft and goes off to carry out his preflight checks before doing the ground run.
The SAR Standby aircraft at the SAR Helipad No 5 Squadron
Upon seeing the copilot and crewman waiting for him, satisfied that the preflight checks have been done presumable twice, he walks around the aircraft and carries out his checks. The captain then straps into his right-hand seat with the copilot in the left-hand seat, connects to the external AC or DC on a trolley accumulator and with the DC buses and some AC buses energised, begins the challenge-and-response prayerful ritual with his copilot for the internals and crewman for the externals. There is a specific dialogue in this, not the Hollywood, "Check" to the items called out by the copilot. For instance, on the pre-start, the copilot starts with "External or Internal Power", and the aircraft commander responds with "External DC on", or "Seat and Pedals" and the response will be "Adjusted my side, check your side". This way, the actual check of each item is executed in detail by the captain, and cross-checked by monitoring by the copilot.
Formation flight over Sabah's west coast
After the pre-start checks, it is time to start No 1 Engine. On the Nuri, a single-engine ground run, a full-ground run or any flying sortie begins with starting No 1 Engine, the one on the left as seen from inside the cockpit. This is because the Nuri is constructed with a feature known as the rotor lockout system, which while in accessory drive selected, diverts the power from No 1 Engine's input bevel gear at the gearbox and rotor drive main bevel gear, via a through-shaft, by freewheeling at the main rotor drive but applies power to the main gearbox accessories such as the hydraulic pumps and generators by powering a secondary gear-train at the rear of the main gearbox. (Imagine a scorpion's tail in its curly poise for a strike, with whatever's happening at its head determining what is being done at the venom sac at the tail. Now you know what we pilots have to deal with when answering examiners' questions on this very favourite topic during our categorisation checks). In this way, all systems on the aircraft can be tested on ground without having to engage the rotors, or powering up both engines. This facilitates system functional checks externally by the crewman or ground crew who carry out some of these duties by climbing up on to the servicing platforms on the starboard side of the aircraft, without worrying about No 2 engine's hot exhausts or hearing damage from a screaming T-58 engine or the added noise and decapitating hazard of rotor blades too close to his bonedome for comfort.
Bambi bucket operations for fire-fighting
As the copilot is seated on the left and has better access to the speed select lever (SSL or "throttle") for No 1 engine, it is his duty to start the engine. The No 1 ignition switch is selected to normal (on) and the No 1 engine firewall shutoff is opened. With the SSL in the fully aft or shut-off position, the starter button is depressed momentarily to energise the starter relays, winding up the compressor spool, drawing air into the combustion chamber, and pilots who haven't completely lost their hearing to years of exposure to screaming turbine engines and grinding and grunting gearboxes can hear the click-clicking of the igniter plugs firing at the ready in their 2-and-8 o'clock positions on the combustion chamber. The winding up of the compressor also runs the engine-driven fuel pump, which draws up fuel from the tanks at low velocity suitable for initial combustion, keeping the fuel waiting at the stop-cock, ready to rush into the atomisers encircling the combustion chamber in two bands. The recipe is almost right, with compressed air and ignition, and all that's missing is fuel. The appropriate mix for this recipe, to obtain the right fuel-air mix occurs at about 19 to 22% compressor turbine speed. This is when the throttle is advanced to the ground idle position, the stop-cock opens to spray fuel into the combustion chamber and then the engine fires up.
Flying on the edge of a storm cloud en route KK to Labuan
Once the engine has settled merrily at about 45-55 % compressor turbine speed upon starter automatic dropout, the throttle is then advanced to 104% power turbine speed, after which all main gearbox accessories are spinning at their 100% optimums. The generators are called on line. With alternating current driving the AC buses and the transformer/rectifiers powering the DC buses, the lubrication, primary hydraulic and auxiliary hydraulic pumps whizzing away, the full system check can proceed. The aircraft captain checks the primary and auxiliary servos which move the swash plates and rotary rudder  spider for proper function and bypass in case of servo pressure failure and accompanying hydraulic lock. The automatic stabilisation equipment computers and devices are checked for function and correction within error limits to determine and predict their dependability in flight. The centre-of-gravity trim, the roll bar lag amplifiers, pitch bar, barometric altitude check and the yaw proportional band check being amongst these, are technical in nature, so I shall pass over the descriptions of these rather in-house fraternity rituals. While the captain and copilot identify and confirm all is well inside the cockpit, the crewman provides external affirmation by confirming the corresponding movements of the servos from the outside, complete with the functional check of the rescue winch and the underslung hook assembly.
Night-stopping at Sepulot due to bad weather
Once all system checks are satisfied, on a single-engine ground run, shutdown procedures would follow. For full ground runs or departures, next on the item is the rotor engagement. Remember that all this while the rotor lockout has allowed the accessories to run without the rotors turning. In order to engage the rotor systems, the aircraft captain fires up No 2 engine, releases the rotor brake and allows the main rotor speed to build. No 2 engine, now driving the main rotor,  is gently brought up to 100% power turbine speed. As No 2 engine is about to reach 100% power turbine speed, it gradually takes over the duty of driving the main gearbox accessories from No 1 engine's through shaft. Because the rotor lockout system was riding on the No 1 engine's power train, and its duties were just usurped by No 2 engine, it would be prudent now for that power to be used to drive the rotors and transmission system in concert with No 2 engine.

To enable this, No 1 engine is brought down to ground idle, and the accessory drive switch now selected to "flight". A nifty set of springs and cages riding on the through-shaft are unleashed, not too unlike the ribs of an umbrella, they now release driving the through-shaft, engage the outer cam races and drive the input gear wheel but oh so cleverly freewheel at the rear secondary gear train!! Now, instead of transmitting engine power to the accessories in a backdoor manner, No 1 engine's input bevel gear is ready to engage the main bevel gear.  The No 1 engine is gently throttled forward. Once it reaches optimum power turbine speed, it  contributes power alongside No 2 engine to the entire transmission and rotor system. Everyone is happy now, all systems have been checked and proven functional and both engines are sharing the rotor and transmission load. The SAR standby crew know that on a quick-start, they can be airborne in minimum time and have checked that all the aircraft primary systems and role equipment are behaving well enough to face mission assignment. Now, shutdown can take place and normal standby resume till sunset.
On anti-terrorism standby in Tawau
After shutdown, the crew walks around the aircraft to ensure that all is okay with the dame Nuri after the rigours of the ground run before the rest of the world starts waking. Minor discrepancies and niggles are referred to the ground crew who vow to clear these up. If anything major surfaces, the aircraft commander confers with the squadron executives whether to snag the aircraft and suspend SAR standby readiness till the snag is rectified or get another aircraft configured for SAR duties whilst rectification is carried out.
The crew then remains on readiness till SAR watch is over at day's end.

This description holds true for most instances of a single-engine or full-ground run. There are times when away from a main base or proper technical support, an accessory drive switch may run foul, mechanically or in  its electrical actuation. During a preceding shut-down, the accessory drive switch may be stuck in flight mode, or before a start-up, pre-flight checks may show the switch not rolling over to flight and back to ground upon selection and deselection of the accessory drive switch. (Yes, the very gremlins that fool around here allowed some mischievous night-stop with fair maidens once in a foreign land, but this blog is to protect the guilty so I ain't sayin' nuthin'!!)

This would require what is known as "emergency rotor engagement". This is when No 2 engine is started first, providing direct drive to the main rotor and accessories (instead of the routine No 1 engine start, running all accessories and then getting No 2 engine to gently take over in preparation for calling No 1 engine on line to join in the powering of all systems through the front door). It is not the  most healthy way to start-up and rotor engage. By starting on No 1 engine first through the rotor lockout system, all pumps and lubricants and servos are already running at 100% efficiency before the heavy work of taking up a rotor system coming to life. Emergency rotor engagement then, engages the rotor dependent on the rotor driving the pumps in slow build-up  in parallel with the rotor RPM. It is harsher than having all pressures ready as in a regular start. Therefore Nuri aircrew know that this is an emergency procedure in case of accessory drive failure away from full technical support for rectifying the failure, allowing for that one-time flight back to home base or detachment base where technical support can be called on for rectification. That, as well as we sometimes have to do it during our categorisation exams, to show the examiners that we are able to engage the rotor systems at low main gearbox lube pressures, and worthy of being in the pilot's seat!
This walk down memory lane hangs in the mists of days gone past. Perhaps my memory does not serve me well. I have lost out on precise figures and technical details. But what my memory will never erase is the many familiar nooks and crannies of the Nuri, the smell of hydraulics drying on her fuselage skin or the unmistakable beat of her rotors tempered by the bifilar  and beanie cap assembly.

She is still my first love.


  1. Strange you described her like it was just yesterday.

  2. I think it is always going to be like it was just yesterday with her. Sometimes when you have loved one as long as this, being apart doesn't take her away from your veins.