Centaurus
24th Jul 2017, 14:53
In 1948 I was 16 and working as a general hand with the Sydney Morning Herald Flying Services based at Camden NSW. The company had two DC3s and three Lockheed Hudsons as freighters to deliver newspapers to destinations in northern NSW. Among other duties my job was to load the papers into the aircraft, lay a flare path and standby to start engines. With enough overtime accrued I was allowed to fly on these trips. My job then was to make the coffee (awful stuff called Chicory coffee) and help the co-pilot to drop the newspapers overboard from a ramp in the aircraft. I was allowed to sit in the copilots seat and the captain would teach me how to fly straight and level.
Also in February 1948 the RAAF had an accident which not only killed the 16 crew and passengers but was one of the most disastrous in the history of the RAAF. The aircraft was A73-11, a Lincoln bomber, a larger and more powerful version of the wartime Avro Lancaster. Both were equipped with four Rolls Royce Merlin in-line liquid cooled engines. While doubtless the accident would have been covered by all Australian newspapers and wireless, I was unaware of the story until in 1953 I was posted to fly Lincolns at RAAF Base Townsville.
Both as a aircraft loader at Camden and later flying Lincolns at Townsville, it was rare to go to the trouble of making a load sheet and centre of gravity calculations in those days. In general, load was distributed equally between compartments and not always weighed. I dont recall ever using a specialised whiz-wheel slide rule at Camden and only on rare occasions on Lincolns. Also while the HFS aircraft were dedicated freighters with metal floors, the Lincoln bomber version only had seats for the crew which then was a pilot and co-pilot, navigator and signaller and two air gunners.
Freight could be carried in special panniers attached to the bomb release hooks in the bomb bay or merely shoved into the fuselage wherever there was room between the two spars. Passengers in the Lincolns sat on the fuselage floor because there were no passenger seat or safety harnesses. It was most unsatisfactory state of affairs but a fact of life in those days. In fact my first flight in an aeroplane was in 1948 at Camden in a Lockheed Hudson along with several other mechanics along for the short ride to test a new engine. We sat or lay down on the fuselage floor with no restraint as there were only the two crew seats for the pilot and co-pilot.
The Lincoln accident occurred at RAAF Base Amberley. The aircraft carried four crew and 12 passengers who were all RAAF ground staff. They sat where they could but mostly towards the tail where there was more room than up among the crew. Excluding personal luggage the manifest showed six Merlin cylinder blocks weighing 289lbs each (1734 lbs total), 8 gallons of dope, 8 gallons of thinners, 18 gallons of methylated spirits. Total freight around 2194lbs. Distribution of the engine blocks was approximately half way down the fuselage and not strapped to the floor. Other freight was placed aft of the rear door and no restraints. The C of G was found to be outside the aft limit for take off from Laverton.
The aircraft departed Laverton at 1415 for Amberley cruising at 8000 feet. Weather was fine. ATC cleared the Lincoln for a straight-in approach to Runway 05. It appeared to be lower and faster than usual. It touched down in a tail high attitude approximately 300 ft after crossing the threshold. After travelling a short distance, the aircraft then bounced, rising to about five feet. From eyewitness reports, attempts were made by the crew to force the aircraft onto the runway but this only resulted in three more bounces.
When about 600 feet from the upwind end of the runway, engine power was applied to make a go around. It is estimated by ground observers that, by this stage, the airspeed of the Lincoln had decreased to approximately 80-85 knots.
The Lincoln was seen to climb slightly, level out at 100 feet, after which the nose rose sharply to place the aircraft in a climbing attitude of 40 degrees. After a further few seconds the attitude changed sharply to a climb of 80 degrees. With all engines roaring at presumably under full power, the aircraft attained an altitude of approximately 500 feet when, with no forward speed, the port wing slowly dropped and the aircraft steadily accelerated until the port mainplane stuck the ground on a vertical position. By this time the fuselage was parallel with the ground.
The aircraft caught fire immediately and although the fire tender arrived shortly after the crash, the fire could not be sufficiently controlled to extricate the crew or passengers. The crash site was 400 yards from the end of runway 05 and displaced 100 yards left of the runway.
The accident was caused by a bad load distribution of freight and passengers for the landing, which resulted in the C of G being placed outside the aft limit. This situation occurred principally through the carriage of freight in an aircraft not designed for such a purpose.
When the undercarriage was retracted for the go-around, the C of G moved further aft and with flaps fully down, the engine power was increased to normal take off power. At this stage the nose commenced to rise; the pilot used full forward stick and trimmed the nose down in an attempt to lower the nose. Then, probably as a last resort, full over-ride maximum power was used which only accentuated the already critical situation. The aircraft then became uncontrollable and stalled at a height of approximately 500 feet with a fuselage angle of 80 degrees to the horizontal.
Lincoln Handling trials.
Handling trials were undertaken by ARDU at Laverton to determine the stability and longitudinal control of the aircraft with various flap settings at different C of G positions. As anticipated, during a baulked approach, the aircraft had barely sufficient downward elevator for the crew to maintain fore and aft control with C of G aft limit, flaps fully down, power combination of max power of 3000rpm/+18 psi boost and speed allowed to decrease to 85 knots before going around.
Subsequent to these tests, the following changes were made to Lincoln operating procedures: Aft C of G limit brought forward and when going around from a baulked approach, the drag portion of the flap was to be removed as quickly as possible to improve elevator control.
.
By the time I arrived at Townsville in April 1953, RAAF Pilots Notes Lincoln had been amended to read: It is essential to raise the flaps to half down before the undercarriage is selected up otherwise an uncontrollable nose up change of trim may be experienced at loadings near the aft C of G limit; this is aggravated by the use of full power.
That warning was in my mind when during a period of night circuits with a new pilot, we were on three engines downwind for a practice asymmetric landing on Townsville Runway 01 with the No.1 engine throttled back to zero thrust (i.e. not feathered) The student handled the Lincoln well on three engines and mid downwind asked me to select flaps to one quarter. On selecting the flap lever to neutral as the flaps indicator reached one quarter, I was startled to see the flap lever break off in my hand leaving the hydraulic selector under the floor to move to full flap. The nose reared upwards but fortunately I was able to take control from the bemused student and bring the No 1 engine along with the other engines, to full power as the airspeed was rapidly falling with the ever increasing nose up change of trim.
If we had been landing with one engine feathered we would have been hard pressed to maintain control.
The airspeed meanwhile had fallen to 90 knots even with full power in level flight and the control column was almost on the forward stop.
In this unusual configuration I could hold height until on final and after advising ATC we had no choice but land because we couldnt go around with full flap, a safe landing was made. Corrosion in the flap lever caused the failure.
............................................................ .................................
A quick thinking pilot and a happy ending
The pilot was Bob Birch with whom I later flew in Air Nauru. He had flown Typhoons at the end of WW2 and at the time of this incident was a DC3 first officer with TAA. For brevity I shall edit his report to the essentials. Bob was to ferry a Tiger Moth from Mackay to Essendon.
He wrote: As I had not flown a Tiger Moth for nine months a short flight would serve the dual purpose of providing familiarisation and giving a very helpful resident a joy ride. The runway was to be used because of a series of deep ditches crossing the aerodrome for wet-season drainage. Checks were carried out in the usual DH82 fashion while taxying. Flying controls were checked and found to be free, full and correct as expected.
On take-off the machine waddled down the runway then leapt into the air of its own accord. I was suddenly aware of climbing with 30 knots on the clock, the auto slats standing open like the legendry claws of fate and the aircraft nose still rising despite the fact that the stick was full forward. Not a pretty picture. To gain airspeed the machine was stood on its port wing tips: the nose dropped, speed increased and problem number one was solved. Problem number two soon emerged the aircraft insisted on a tight left turn which could not be controlled by rudder; not really disturbing as a turn was necessary to return for landing. However, the left turn took us straight towards about six HF radio masts complete with aerials and guy wires.
Reduced bank produced a hop over that obstacle and a slipping descending turn was made up to line up with the runway. Beaut! Except for problem number three, which became evident as the wings were levelled for landing.; the reduction was insufficient and once again we were climbing again. Third time around proved lucky, the machine made quite a respectful landing by stalling completely as the wings came level. Almost a three-pointer; not bad after nine months.
Had anyone been interested, three circuits with stick full forward in less than two minutes would have been some sort of record. I apologised to the local passenger for the scary ride, disgustedly kicked one tyre hard, and returned to Melbourne. Later the aircraft flew normally after correction.
So, what went wrong? The control box was incorrectly assembled and at some stage the down-elevator became slack. Back stick gave up-elevator correctly. As the stick moved forward, slackness in the down-elevator cables allowed the elevators to fall under their own weight. On take-off as the stick was moved forward, the elevators took the streamlined position behind the tailplane, and airspeed increased. Unknown to me was the fact that in straight and level flight the elevators are depressed by about 15 to 20 degrees. With the elevators streamlined behind the tailplane, a strong nose- up pitch force is experienced by the aircraft. Hence the aircraft left the ground in a tail-down position.
Fortunately I had received good training with the RAAF and RAF on Wirraways, Masters, Spitfires and Typhoons in authorised low flying, stalls, spins, aerobatics and recovery from unusual attitudes. All proved valuable.
..
In both the events described The Lincoln overshoot crash and the Tiger Moth story, extreme nose high attitudes at full power and low altitude were the start of an unusual attitude. Of course the Lincoln was in more dire straits because of being outside of the aft limit of the C of G when it went around and such was the extreme nose high attitude that recovery was impossible from 500 feet. The Tiger Moth pilot was able to fall back on his unusual attitude training by turning the nose high attitude and falling airspeed into a steep angle of bank by using full aileron to get the nose to fall to level flight, thus increasing speed.
In todays flying schools it is often the case where instructors themselves with perhaps only 250 hours before receiving their rating, have little knowledge of such emergency manoeuvres. Yet there is no shortage of this basic unusual attitude recovery information to be found on the internet aviation websites. Student pilots should be encouraged to look for themselves rather than wait for their instructor to point them in the right direction if indeed the instructor knows himself.
The last word in recovery from a nose high wings level unusual attitude can be found in the Boeing 737 Flight crew Training Manual. The recovery technique can be applied to most types of aircraft.
Edited for brevity:
Nose High, Wings Level.
At full thrust settings and very low airspeeds, the elevator working in opposition to the stabilizer will have limited control to reduce the pitch attitude. In this situation the pilot should trade altitude for airspeed and manoeuvre the flight path back toward the horizon. This is accomplished by the input of up to full nose-down elevator and the use of some nose-down stabilizer trim.
If normal pitch control inputs do not stop an increasing pitch rate, rolling the airplane to a bank angle that starts the nose down should work. Bank angles of about 45 degrees, up to a maximum of 60 degrees, could be needed. Unloading the wing by maintaining continuous nose-down elevator pressure keeps the wing angle of attack as low as possible, making the normal roll controls as effective as possible. With airspeed as low as stick shaker onset, normal roll controls up to full deflection of ailerons and spoilers may be used.
The rolling maneuver changes the pitch rate into a turning maneuver, allowing the pitch to decrease. Finally, if normal pitch control then roll control is ineffective, careful rudder input in the direction of the desired roll may be required to induce a rolling manoeuvre or recovery. Too much rudder applied too quickly or held too long may result in loss of lateral and directional control. Because of the low energy condition, pilots should exercise caution when applying rudder. After the pitch attitude and airspeed return to a desired range, the pilot can reduce the angle of bank with normal lateral flight controls and return the airplane to normal flight.
There is an old saying that you must learn from the mistakes of others. You cant possibly live long enough to make them all yourself. Certainly true in aviation.
Also in February 1948 the RAAF had an accident which not only killed the 16 crew and passengers but was one of the most disastrous in the history of the RAAF. The aircraft was A73-11, a Lincoln bomber, a larger and more powerful version of the wartime Avro Lancaster. Both were equipped with four Rolls Royce Merlin in-line liquid cooled engines. While doubtless the accident would have been covered by all Australian newspapers and wireless, I was unaware of the story until in 1953 I was posted to fly Lincolns at RAAF Base Townsville.
Both as a aircraft loader at Camden and later flying Lincolns at Townsville, it was rare to go to the trouble of making a load sheet and centre of gravity calculations in those days. In general, load was distributed equally between compartments and not always weighed. I dont recall ever using a specialised whiz-wheel slide rule at Camden and only on rare occasions on Lincolns. Also while the HFS aircraft were dedicated freighters with metal floors, the Lincoln bomber version only had seats for the crew which then was a pilot and co-pilot, navigator and signaller and two air gunners.
Freight could be carried in special panniers attached to the bomb release hooks in the bomb bay or merely shoved into the fuselage wherever there was room between the two spars. Passengers in the Lincolns sat on the fuselage floor because there were no passenger seat or safety harnesses. It was most unsatisfactory state of affairs but a fact of life in those days. In fact my first flight in an aeroplane was in 1948 at Camden in a Lockheed Hudson along with several other mechanics along for the short ride to test a new engine. We sat or lay down on the fuselage floor with no restraint as there were only the two crew seats for the pilot and co-pilot.
The Lincoln accident occurred at RAAF Base Amberley. The aircraft carried four crew and 12 passengers who were all RAAF ground staff. They sat where they could but mostly towards the tail where there was more room than up among the crew. Excluding personal luggage the manifest showed six Merlin cylinder blocks weighing 289lbs each (1734 lbs total), 8 gallons of dope, 8 gallons of thinners, 18 gallons of methylated spirits. Total freight around 2194lbs. Distribution of the engine blocks was approximately half way down the fuselage and not strapped to the floor. Other freight was placed aft of the rear door and no restraints. The C of G was found to be outside the aft limit for take off from Laverton.
The aircraft departed Laverton at 1415 for Amberley cruising at 8000 feet. Weather was fine. ATC cleared the Lincoln for a straight-in approach to Runway 05. It appeared to be lower and faster than usual. It touched down in a tail high attitude approximately 300 ft after crossing the threshold. After travelling a short distance, the aircraft then bounced, rising to about five feet. From eyewitness reports, attempts were made by the crew to force the aircraft onto the runway but this only resulted in three more bounces.
When about 600 feet from the upwind end of the runway, engine power was applied to make a go around. It is estimated by ground observers that, by this stage, the airspeed of the Lincoln had decreased to approximately 80-85 knots.
The Lincoln was seen to climb slightly, level out at 100 feet, after which the nose rose sharply to place the aircraft in a climbing attitude of 40 degrees. After a further few seconds the attitude changed sharply to a climb of 80 degrees. With all engines roaring at presumably under full power, the aircraft attained an altitude of approximately 500 feet when, with no forward speed, the port wing slowly dropped and the aircraft steadily accelerated until the port mainplane stuck the ground on a vertical position. By this time the fuselage was parallel with the ground.
The aircraft caught fire immediately and although the fire tender arrived shortly after the crash, the fire could not be sufficiently controlled to extricate the crew or passengers. The crash site was 400 yards from the end of runway 05 and displaced 100 yards left of the runway.
The accident was caused by a bad load distribution of freight and passengers for the landing, which resulted in the C of G being placed outside the aft limit. This situation occurred principally through the carriage of freight in an aircraft not designed for such a purpose.
When the undercarriage was retracted for the go-around, the C of G moved further aft and with flaps fully down, the engine power was increased to normal take off power. At this stage the nose commenced to rise; the pilot used full forward stick and trimmed the nose down in an attempt to lower the nose. Then, probably as a last resort, full over-ride maximum power was used which only accentuated the already critical situation. The aircraft then became uncontrollable and stalled at a height of approximately 500 feet with a fuselage angle of 80 degrees to the horizontal.
Lincoln Handling trials.
Handling trials were undertaken by ARDU at Laverton to determine the stability and longitudinal control of the aircraft with various flap settings at different C of G positions. As anticipated, during a baulked approach, the aircraft had barely sufficient downward elevator for the crew to maintain fore and aft control with C of G aft limit, flaps fully down, power combination of max power of 3000rpm/+18 psi boost and speed allowed to decrease to 85 knots before going around.
Subsequent to these tests, the following changes were made to Lincoln operating procedures: Aft C of G limit brought forward and when going around from a baulked approach, the drag portion of the flap was to be removed as quickly as possible to improve elevator control.
.
By the time I arrived at Townsville in April 1953, RAAF Pilots Notes Lincoln had been amended to read: It is essential to raise the flaps to half down before the undercarriage is selected up otherwise an uncontrollable nose up change of trim may be experienced at loadings near the aft C of G limit; this is aggravated by the use of full power.
That warning was in my mind when during a period of night circuits with a new pilot, we were on three engines downwind for a practice asymmetric landing on Townsville Runway 01 with the No.1 engine throttled back to zero thrust (i.e. not feathered) The student handled the Lincoln well on three engines and mid downwind asked me to select flaps to one quarter. On selecting the flap lever to neutral as the flaps indicator reached one quarter, I was startled to see the flap lever break off in my hand leaving the hydraulic selector under the floor to move to full flap. The nose reared upwards but fortunately I was able to take control from the bemused student and bring the No 1 engine along with the other engines, to full power as the airspeed was rapidly falling with the ever increasing nose up change of trim.
If we had been landing with one engine feathered we would have been hard pressed to maintain control.
The airspeed meanwhile had fallen to 90 knots even with full power in level flight and the control column was almost on the forward stop.
In this unusual configuration I could hold height until on final and after advising ATC we had no choice but land because we couldnt go around with full flap, a safe landing was made. Corrosion in the flap lever caused the failure.
............................................................ .................................
A quick thinking pilot and a happy ending
The pilot was Bob Birch with whom I later flew in Air Nauru. He had flown Typhoons at the end of WW2 and at the time of this incident was a DC3 first officer with TAA. For brevity I shall edit his report to the essentials. Bob was to ferry a Tiger Moth from Mackay to Essendon.
He wrote: As I had not flown a Tiger Moth for nine months a short flight would serve the dual purpose of providing familiarisation and giving a very helpful resident a joy ride. The runway was to be used because of a series of deep ditches crossing the aerodrome for wet-season drainage. Checks were carried out in the usual DH82 fashion while taxying. Flying controls were checked and found to be free, full and correct as expected.
On take-off the machine waddled down the runway then leapt into the air of its own accord. I was suddenly aware of climbing with 30 knots on the clock, the auto slats standing open like the legendry claws of fate and the aircraft nose still rising despite the fact that the stick was full forward. Not a pretty picture. To gain airspeed the machine was stood on its port wing tips: the nose dropped, speed increased and problem number one was solved. Problem number two soon emerged the aircraft insisted on a tight left turn which could not be controlled by rudder; not really disturbing as a turn was necessary to return for landing. However, the left turn took us straight towards about six HF radio masts complete with aerials and guy wires.
Reduced bank produced a hop over that obstacle and a slipping descending turn was made up to line up with the runway. Beaut! Except for problem number three, which became evident as the wings were levelled for landing.; the reduction was insufficient and once again we were climbing again. Third time around proved lucky, the machine made quite a respectful landing by stalling completely as the wings came level. Almost a three-pointer; not bad after nine months.
Had anyone been interested, three circuits with stick full forward in less than two minutes would have been some sort of record. I apologised to the local passenger for the scary ride, disgustedly kicked one tyre hard, and returned to Melbourne. Later the aircraft flew normally after correction.
So, what went wrong? The control box was incorrectly assembled and at some stage the down-elevator became slack. Back stick gave up-elevator correctly. As the stick moved forward, slackness in the down-elevator cables allowed the elevators to fall under their own weight. On take-off as the stick was moved forward, the elevators took the streamlined position behind the tailplane, and airspeed increased. Unknown to me was the fact that in straight and level flight the elevators are depressed by about 15 to 20 degrees. With the elevators streamlined behind the tailplane, a strong nose- up pitch force is experienced by the aircraft. Hence the aircraft left the ground in a tail-down position.
Fortunately I had received good training with the RAAF and RAF on Wirraways, Masters, Spitfires and Typhoons in authorised low flying, stalls, spins, aerobatics and recovery from unusual attitudes. All proved valuable.
..
In both the events described The Lincoln overshoot crash and the Tiger Moth story, extreme nose high attitudes at full power and low altitude were the start of an unusual attitude. Of course the Lincoln was in more dire straits because of being outside of the aft limit of the C of G when it went around and such was the extreme nose high attitude that recovery was impossible from 500 feet. The Tiger Moth pilot was able to fall back on his unusual attitude training by turning the nose high attitude and falling airspeed into a steep angle of bank by using full aileron to get the nose to fall to level flight, thus increasing speed.
In todays flying schools it is often the case where instructors themselves with perhaps only 250 hours before receiving their rating, have little knowledge of such emergency manoeuvres. Yet there is no shortage of this basic unusual attitude recovery information to be found on the internet aviation websites. Student pilots should be encouraged to look for themselves rather than wait for their instructor to point them in the right direction if indeed the instructor knows himself.
The last word in recovery from a nose high wings level unusual attitude can be found in the Boeing 737 Flight crew Training Manual. The recovery technique can be applied to most types of aircraft.
Edited for brevity:
Nose High, Wings Level.
At full thrust settings and very low airspeeds, the elevator working in opposition to the stabilizer will have limited control to reduce the pitch attitude. In this situation the pilot should trade altitude for airspeed and manoeuvre the flight path back toward the horizon. This is accomplished by the input of up to full nose-down elevator and the use of some nose-down stabilizer trim.
If normal pitch control inputs do not stop an increasing pitch rate, rolling the airplane to a bank angle that starts the nose down should work. Bank angles of about 45 degrees, up to a maximum of 60 degrees, could be needed. Unloading the wing by maintaining continuous nose-down elevator pressure keeps the wing angle of attack as low as possible, making the normal roll controls as effective as possible. With airspeed as low as stick shaker onset, normal roll controls up to full deflection of ailerons and spoilers may be used.
The rolling maneuver changes the pitch rate into a turning maneuver, allowing the pitch to decrease. Finally, if normal pitch control then roll control is ineffective, careful rudder input in the direction of the desired roll may be required to induce a rolling manoeuvre or recovery. Too much rudder applied too quickly or held too long may result in loss of lateral and directional control. Because of the low energy condition, pilots should exercise caution when applying rudder. After the pitch attitude and airspeed return to a desired range, the pilot can reduce the angle of bank with normal lateral flight controls and return the airplane to normal flight.
There is an old saying that you must learn from the mistakes of others. You cant possibly live long enough to make them all yourself. Certainly true in aviation.