A Flutter In Ambush
A snaphot from the past
It was 1960. Italy was going towards a fast and intense industrial development, in full Economic Miracle. The DC (Christian Democrats) were governing the country; in the movie theaters, notwithstanding the censorship, Fellini’s “La dolce vita” was reaping success; soon after, the Leonardo da Vinci airport in Fiumicino opened. There was a great enthusiasm, a will to do, create, progress, take part in the Country’s development.
In that sunny early July afternoon, in a hangar of the Capodichino airport, where the Partenavia flight line was situated, Gino and Nino Pascale were busy, together with their trusted specialist Enzo Sorgente, in inspecting the aircraft with the signs I-VIVA that, on the previous day, had flown for the first time. It was a P57 Fachiro that the newly established Partenavia Costruzioni Aeronautiche, the company wanted so badly by the Pascale brothers, mass produced for the first time in the Arzano plant, not far from the airport. The two brothers, passionate about aviation since their childhood, were in that wonderful age between thirty and forty, when nothing seems impossible and the energy, especially in a couple, is endless. The P57 Fachiro represented exceptional qualities. It was a four-seater that in Italy, in those times, was an absolute novelty in the sector of the light planes. Powered by a 180 hp engine, its performance allowed to carry four people at full load at approximately 200 km/h on routes such as the Naples – Genoa. The I-VIVA had the serial number 2 and was destined for the Bari Aero Club, whose instructor, Commander Carlo Citelli, a test pilot and a former Air Force pilot, did really appreciate the aircraft. He had met the Pascales some years after the war, while on transit in Capodichino with a rickety Fairchild, a war residue.
In those times, when a private plane landed at an airport, the crew was welcomed as a guest and helped in all operations as much as possible. The circle of the aviators and of the aviation operators was restricted, and between them there was a great solidarity, also for that concealed sense of admiration felt for those who “were going in the air”. On a flight on the previous day, the pilot had felt an awkward vibration of the I-VIVA right wing, attributed to a badly locked large inspection hole. After fixing that issue, the Pascales decided for a test flight.
In those days, Capodichino was very different from today: the commercial traffic consisted in a few national collections; then, there was the Aero Club school and some flight of the Air Force or from the U.S. Navy base. The airport was never crowded, the control tower managed the traffic volume without problems, and usually the staff was well-disposed towards the pilots of local flights. After completing the pre-flight tests and inspections, Gino seated at the controls, with Nino next to him to write down the data. The control tower gave the authorization to India – Victor India Victor Alfa “to taxi to the waiting point, raceway 240°”. To fly with their “creatures”, check their conditions and their efficiency, had always been for the Pascale brothers, one of the things they considered among the most important in their activity. So, that day, they had to check if the inconvenience detected the other day had disappeared. Both brothers had obtained the civil pilot license in 1950 with the Macchi MB308, but, while Nino was less interested in continuing the pilot activity, busy as he was with managing the plant, Gino had consolidated his experience on various airplanes such as the Stinson L5, the Fiat G46, and many more, while he was doing many shop flights for the Partenavia planes, with a special authorization granted by Civilavia1, in his quality of designer of the planes. He had also obtained in Rieti the “C license” for gliding, having as an instructor the great Adriano Mantelli, a pilot that he had always deeply admired and followed in his enterprises, since when, articipating in 1942 at the Concorso Nazionale Modelli Volanti2 in Asiago, he saw him doing aerobatics with the glider CAT20.
After the usual engine tests, they asked for the authorization to take off, which the controller gave them on the spot. The weather was almost fine; the temperature was 26°C and the wind was weak. The throttle went all in, the engine revving up to the top, the brakes were released: in a few hundred meters, the I-VIVA was up in the air, the VSI growing, all was fine, and in their eyes, they had the breathtaking view of the gulf, framed by the Vesuvius and the Sorrento peninsula, with Capri in the background.
The area assigned to the test was between Portici and Torre del Greco; there, it was possible to climb up. As previously planned, they reached 3000 ft. (1000 m), with the intention, at that altitude, to reach with a light dive and at full speed, the Vne (Never Exceed Speed), that is, the speed that the pilot must never exceed. So, they began the test… the speed gradually increased… 200, 220, 250, 270 – all fine – the airplane went down smoothly, gaining speed, when all of a sudden, something similar to an earthquake burst. The wings wavered at an incredible width, while the aircraft, with a dull thunder, got out of control. Gino, instinctively, managed to cut off the engine, while, out of the corner of his eye, he saw something ripped off the left half-wing. At that point, the earthquake stopped.
Gino shouted at Nino, “We have lost the left aileron”. And Nino, in reply, “The right one is gone too”. Gino added: “Siamo fottuti!*”
*” We are lost ! ”
In a matter of seconds, the incredibly violent phenomenon had torn off both ailerons. That was luck, because, on the contrary, the wing would have given up. Even better, the rupture was perfectly symmetrical, so that it had left unchanged the balance when rolling. Now, the aircraft was descending at moderate speed. Regaining their senses after the powerful burst of adren aline, the two brothers took stock of the situation, which appeared desperate.
Obviously, the handwheel was controlling only the “nose up and nose down”, and the pedal board, untouched, was controlling the rudder. The aircraft was still keeping the wings leveled, but, at any moment, it could begin to tilt and enter into a deadly spiraling. And that’s exactly what happened soon after: by instinct, Gino acted on the pedal and the aircraft responded, regaining the correct cross attitude.
They felt they still had some hope: all was not lost yet. The aircraft behavior reappeared on both the left and right side, and Gino always straightened it with the pedal. They still were in the Portici area, and the aircraft nose was pointed towards Capodichino. Gino wanted to communicate with the control tower, but the microphone was out of reach. Nino got hold of it and established the contact with Capodichino, “We have a serious emergency, here. We’re trying to reach the field”.
The possibility to control the cross attitude of the aircraft with the rudder is due to what, in flight mechanics, is called “dihedral effect”. This effect is common in high-wing airplanes like the Fachiro and represents an important requisite of the flight qualities requested by the current airworthiness standards. The effective presence of the dihedral effect, in this case, was a life saver.
“Torre Capo, we can see the field, but we cannot align to the strip. We will try to land crosswise!”
The Capodichino runway is 60°- 240° oriented and the heading of the I-VIVA was about 340°, hence almost 90° with the runway, but turning in those conditions was clearly a hazard. They began the long final and, very carefully, they activated the flap control, which, in the Fachiro, is manually controlled via a bar installed between the two pilot seats. Up to the first notch, about 15°, they detected no side dips, but they did not insist.
They completely cut off the engine and, leaving the control tower to their right, they began the short final approach, trying to reduce the speed as much as possible. With the increase of the approach angle, the aircraft began to dip and, when they tried to adjust it by pedal, it yawed. So, they gave up. Finally, they touched the grass at about one hundred meters off the runway, passing over its curb with a jolt. The speed, low by then, finally allowed to perform the alignment and continue along the axis. We realized that the I-VIVA was followed by a queue of vehicles: firefighters, ambulances, jeeps, etc. The Pascales looked at each other and, agreeing silently, decided to quickly continue taxiing to the hangar: It is in the company’s interest trying to play down the event. Once in the hangar, Enzo Sorgente tried to keep the people out and, seeing the dire conditions of the wings, incredulous and stricken, burst into tears. In the meanwhile, the two brothers, dazed and happy to be back on the ground, asked for something to drink and to be left alone for a few minutes.
The report on the event, which the airport authority immediately demanded, described in short the circumstances and the cause of the emergency: loss of the aircraft’s side control. After about an hour from landing, a jeep of the police arrived at Capodichino to deliver to the Aero Club a fragment fallen from a small airplane while flying over Portici. It was an aileron of the I-VIVA; the other was most likely at the bottom of the sea. The tremendous phenomenon that had occurred is among those classified as flutters, like the fluttering of a bird’s wing. It is technically defined as an oscillating movement in which interact aerodynamic forces, elastic forces and inertia forces. Specifically, the flutter that hit the I-VIVA was a binary flutter associated with the bending of the wing flexure and with the rotation of the aileron. Soon after the incident, they made a modification that consisted in balancing the aileron with an appropriate mass, the so-called mass-balancing. With that, one eliminated every chance that the flutter could occur again.
From “The sky is the limit:
an aviation legacy. The story of Tecnam and the Pascale brothers”
Compiled by Stefano Mavilio
Per approfondimenti consulta la fonte
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