Power Loss in Low Energy Flight

Share on facebook
Share on twitter
Share on linkedin

In this edition of Sydney Flyer resident Flight Instructor and Flight Examiner Bill Cooper reflects on why a loss of power in low energy flight can be the most challenging situation a pilot can face

POWER LOSS in LOW-ENERGY FLIGHT

Low energy = low airspeed and height above ground
By Bill Cooper, with credit to an Air Facts article by Parvez Dara

Company training procedures for engine failure on takeoff mandates standard INITIAL ACTIONS and LAND AHEAD policies. Both are prudent and least-risk options, in the unlikely event of occurring. This briefing explores some worst-case low-energy scenarios that have actually happened and decisions/actions that have been taken.

Prelude

Some years ago, at Camden Airport, I walked over to another flying school to cross-hire an aircraft for a Club member. Enroute, I passed and admired the immaculate old Jaguar sedan owned by a member of the Macarthur aristocracy. The lady herself was at the flight line, pre-flighting a Victa Airtourer 2-seater with her FI for some solo aerobatic recency. She departed for the Training Area, returning about 40 minutes later for ‘Circuits on arrival ‘. I was back in my office at the flying school, with the radio on, when a ‘breaking news’ item shook me: ‘ .. an aircraft has crashed at Camden Airport in SW Sydney’ .. and one of ours was out doing dual circuits!

I shot out of the hangar, to see a small smoke cloud curling up beyond the southwest end of the airport, but was very relieved to see our aircraft taxiing in. After parking, the instructor told me that the Airtourer had crashed on upwind, but he’d continued circuits until ATC chased him away as the airport was closing due to the crash. The Jag still sat waiting in the car park, sadly. 

In the subsequent ATSB report, the Victa ‘..experienced loss of power during the initial climb, stalled and spiralled into the front garden of a house across the river from the upwind end of the runway. There was a brief post-crash fire and the pilot did not survive’. The aircraft was apparently capable of normal flight at the time, so fuel starvation/exhaustion was suggested as a likely cause. 

I wondered: Two problems: 

  • One: Why did a serviceable engine slow/stop and 
  • Two: Why did the pilot apparently stall/spin instead of flying the plane onwards to open fields? (which were available then, but are now full of houses) 

Someone trained in aerobatics should be aware of the stall/spin risk, especially near ground, surely?

From the small impact area, the Airtourer had spun in from within circuit height, well below minimum recovery height. Because of the brief post-crash fire, fuel state could not be determined, but it must have been low. Whatever, the sad event shows that we all make mistakes and there were at least two in that crash: low fuel and not moving the stick forward. The lady was held to be an OK aerobatic pilot but rarely flew.  

Power Loss in Low-Energy Flight

An aircraft acquires its energy in the form of speed and height via engine power, so it is in a low-energy mode when it is flying slowly close to the ground, as in emergency procedures practice and during takeoff and landing. Engine failure during these phases is a rare but very high-risk aviation event. 

As uneventful experience is gained, safety training fades and we become complacent. Today, most pilots may go through their whole career incident-free, largely because of mandatory flight reviews and proficiency checks which simulate events and sharpen procedures for the next departure, to be perhaps a Sully-type off-airport emergency, where there are things to do immediately and without hesitation to ward off a disaster. 

In the moments after take-off, an aircraft is vulnerable as it lacks speed, height and may be in a high-drag configuration (flap and gear). Similarly, on the approach, unavailable power late on approach may result in landing short of the runway (e.g., ice in carburettor or fuel lines). 

The pilot, having recently intoned the safety brief mantra in the runup bay, or on the approach, may yet be startled and shocked by the loss of noise and performance. ‘Can’t think!’ Precious seconds whizz past. ‘What to do?? Mind’s a blank’. At this point, pilots may intuitively pull the wheel back when what is required is the opposite.

If the engine quits soon after takeoff, or just before landing, then that is not the time to rummage through any procedure, in digital or written form. You will be best equipped to deal with it if you are:

  1. Aware of the risk, 
  2. Ready to identify a failure and 
  3. Act immediately! 

3 is all about INITIAL ACTIONS, where regular simulated practice can deliver a flurry of Emergency Procedure Muscle Memory actions in a short time:

  1. PITCH ATTITUDE Push toGlide speed* attitude and Trim
  2. REDUCE DRAG: Gear, Flap UP, Centre ball in TC (if Controllable Prop: PULL all the way back)
  3. MIXTURE: Full Rich
  4. FUEL: Change Tanks
  5. BOOST PUMP: ON
  6. CARB. HEAT/ALT. AIR: ON
  7. IGNITION CHECK: ON, try START

*Weight-based, glide speed in Flight Manual is for max. Gross Weight at TKOF, so if the aircraft is lighter, best glide speed is a little lower (though a little extra airspeed is better than less airspeed).

At height, there is time to do these checks, but down low, there is little time, but Beware Over-expectation, i.e., do you really have a problem?

Some time ago A P51 Mustang (lovely!) newly restored at Bankstown is to be delivered to its new owner interstate. The aircraft had been checked and checked, test-flown and a new MR issued, but the aircraft had long been a hangar queen, dismantled worked on, reassembled, thousands of hours’ work expended. The next flight is a critical time in a renewed aircraft’s life. The highly experienced delivery pilot spent time going over the aircraft and its documents. Then, departure time!

Quite a few people gathered, to view the departure. Aircraft fuelled, oil, coolant serviced, the pilot climbs into his gleaming steed. Engine started, everything checked again, warm and ready. Cleared for takeoff, the pilot lines up, advances the throttle and, to the awesome sound of unleashed Merlin, the aircraft hurtles down the runway. Tail up, all going well, rotate .. but what’s that!? A different sound, a change of note? What’s wrong? No time!! Close throttle, Mixture cut off, Fuel off, Ignition off, full braking, end of runway, Bang!, sideways through the fence, gear collapse, slide to a stop. Everything OFF, unbuckle belt, Abandon aircraft. Run! It might blow up.

The abrupt change from gleaming, singing machine to smoking wreck in a field, shocked everyone. What went wrong? Well, nothing, it was just the propeller blade pitch angle changing as it came on- speed (at governed RPM). Over-reacting pilot? Yes, but a live one.. and if the sound had been from a failing engine .. a prudent, life-saving reaction, saving an off-airport landing. He lived to fly again, as did the aircraft, after several thousand hours’ more work!

The Impossible Turn

In safety seminars, ATSB reports and FI (flight instructor) training, it is universally agreed that attempting to turn back to the airport following engine failure below 1000ft will kill you. But if the view ahead is all urban sprawl, with buildings, vehicles, power lines, trees, people, survival is unlikely anyway. So, is the turn really impossible?

At Camden, some years ago, a Bellanca Citabria was doing dual circuits on the 10 grass runway. Soon after a takeoff, the cockpit filled with smoke and heat. The FI took control, whipped the aircraft around 1800 in a near-vertical turn, landing on the adjacent, parallel glider strip. As it touched down, the windscreen was melting and there was a visible fire. The aircraft was abandoned as soon as it had slowed enough and it burned to a blackened wreck, with a few metal bits in a big black circle. The cause was a faulty voltage regulator, mounted on the firewall (ironic name).

The FI acted promptly and perfectly in the circumstances, as the flight path ahead was across a tree-lined river to swampy, rough land. The height lost in the turn minimised flight time as well, to a flat surface, enabling crew survival uninjured. The aircraft did have power available, which may have assisted a safe outcome. Could the performance of this skilled, current aerobatic pilot be replicated by an average Joe?

In one of the Aviation Journals, there was a report of informal experiments with a Mooney cabin single-engine aircraft in how to minimise the height loss in an attempted return to the runway (but done at a safe height!). As I recall, of the bank angles of 200, 400 and 600, the best result (- 320ft) was 600.

A big advantage of this steep turn was that the aircraft was reasonably aligned on rollout. 200 bank was useless, as it put the aircraft too wide of the extended runway centre line to align. Both smaller bank angles produced much more height loss, due perhaps to longer flight paths.

Comment

These three examples of pilot behaviour under pressure can be useful to all pilots:

  • The lady known to handle an aircraft well when everything worked was brought undone by not flying the ‘plane when startled by an issue under the pilot’s control: fuel flow or quantity. Sad;
  • The professional pilot, focussed on the potential for trouble with a complex, recently over-hauled but old aircraft, reacting to a ‘bad’ sound by wrongly pulling the power on an already-committed departure. Duh;
  • The cool, calm professional FI, aware of the risks, paying close attention during a routine circuit, identifying a totally unexpected emergency, taking control, grabbing a discredited technique (return to land) to fix an emerging catastrophe and finally saving the crew in a spectacularly successful emergency landing. Hero!

 

Bill Cooper

Get in touch

Please fill in your enquiry below and someone at SFC will be in touch with you shortly.

Contact Info