Updated on July 12, 2007
If you are flying a pendulum ULM Cosmos equipped with a Chronos 14 wing, read this file and check your aircraft.
I have had to wait years before being able to share my testimony regarding a very serious accident that left my friend Robert Dalmau and his client passenger, Alsio Origlio, permanently disabled. Dalmau can no longer walk; he drags himself along. The neurological damage he sustained has made his life a true hell of suffering. I do not know what became of his passenger, whose identity and physical injuries I am unaware of. This accident occurred in France, at the Gap Tallard airfield on May 26, 1997.
Dalmau considered himself a kind of official pilot for Cosmos, a pioneer in pendulum ULMs. I see from checking the website that this company is the world leader in selling pendulum ULMs. These wings look like this:
Pendulum ULM
This is not a photograph of the Cosmos wing on which Dalmau and his passenger were involved in the accident, but the appearance is very similar.
The incriminated Cosmos pendulum was equipped with a Chronos 14 wing mounted on a Cosmo "bidulum" trolley.
I recently confirmed, in July 2007, that there were still Cosmos pendulum clubs equipped with Chronos 14 wings (at the Nivelles ULM Club in Belgium). I just spoke to Robert, who believes there are still aircraft with this configuration still in service.
Therefore, I strongly urge all owners of trolleys equipped with Chronos 14 wings to urgently perform this check!
Here are the facts.
I have known Dalmau for many years, since the late 1970s. He was one of the pioneers of pendulum ULMs and a promoter of flying on this type of aircraft. He had an impressive number of flight hours. I occasionally rented his aircraft to go for a flight from the airfield where he was based in southern France. The pendulum aircraft from that era was very fun to fly. Without any fuselage, it gave the impression of being an "air bicycle." You could see the open space beneath your feet.
One day in 1997, I came to the Tallard airfield with two friends who wanted to take their first flight. When we arrived, Robert Dalmau had just landed after flying with a client. A skilled pilot, he had sensed "the machine was pulling to the left." He decided to land the wing and inspect it. I helped him carry out the operation. When we examined the leading edge - crossbar joint, I was shocked. At the time, I made extremely precise sketches that were later used by the aeronautical expert in the trial that Dalmau brought against the Cosmos company. Precisely because these drawings were essential pieces of evidence in the trial, I could not mention them for years, during the entire duration of the court case, under penalty of rendering the documents legally invalid. I have not yet been able to locate these drawings in my CD archives. I just spoke to Dalmau, who told me he is retrieving them from his lawyer, Maître Magret, based in Bordeaux, and will send them to me. As soon as I have these drawings, I will scan them and include them on the website.
Therefore, this document contains only a preliminary schematic description.
A pendulum wing is attached to a frame made of lightweight alloy tubes. See the top diagram. This frame has two leading edge - crossbar joints (floating). In the configuration we examined, Dalmau and I saw that both tubes were fastened together by a single threaded rod running the full length and bolted at both ends. At each end, cables forming the upper and lower stays could be attached. As can be seen, the lower stays are attached to the horizontal bar of the "trapeze." These two stays experience very high tension. Therefore, the bolt passing through both tubes is subjected to both tensile and bending forces.
Diagram of the leading edge - crossbar joint assembly
In the configuration of this Chronos 14 wing that equipped the Cosmos "bidulum" aircraft at the time, we can see how the lower stay
Hexerts a bending force on the threaded rod passing through the two tubes. Between the tubes, there are plastic joint couplings. But inside the tubes, there is no sleeve! A sleeve that would have prevented the rod from bending.
This kind of assembly is completely absurd.
As shown in the left-hand drawing, the successive forces applied to this assembly had caused the threaded rod to break right in the middle of the leading edge tube. A threaded rod is the worst possible device for handling alternating bending stresses. In fact, it is the worst imaginable, since the threads themselves act as crack initiation points.
But fortunately, the system remained in place due to the strong lateral tension. See the left-hand drawing.
In reality, the condition of the assembly was even worse. When I obtain the original drawing, readers will be able to see for themselves. I do not wish to reproduce something imprecise from memory. There was another flat piece, 5 mm thick, which was cracked over a 5 cm length. Only 1 cm of metal remained. The conclusion was that Dalmau and his companion had been extremely lucky that day. If he had not performed this inspection, the two young women who had come with me for their first flight would almost certainly have been victims of a serious accident, along with Dalmau, the pilot.
I personally wrote three letters:
- One to the manufacturer.
- The second to the president of the ULM federation.
- The third to the magazine "Vol Moteur," in the form of an informative article I wished to see published in its pages.
I received no response.
Some time later, I learned that Dalmau had been seriously injured while flying a Cosmos aircraft with a Chronos 14 wing.
Sometimes, "one does not listen to warnings." A few months after discovering that these wings were so poorly constructed, Robert bought another one—used.
- The wing looked healthy, he told me.
These were his exact words. It had 200 flight hours. Robert did not perform the same inspection on this wing as we had done together. The failure occurred during takeoff, as he was climbing with a client. This time, the threaded rod was ejected, attached to the lower stay cable. The leading edge did not break, but the cable became entangled in the propeller. As it wound around the shaft, it exerted a violent pull on the trapeze, which Dalmau could not control. The aircraft entered a steep dive and crashed into the ground.
Accident on Cosmos, Chronos 14 wing, May 1997. Pilot: Robert Dalmau. Passenger: Alsio Origlio. Link: Gap Tallard airfield, France
Following this accident, the Cosmos company did not issue any safety warning to buyers of this type of aircraft (according to Robert Dalmau).
That’s it… the facts.
This case has a third chapter. After this serious accident occurred and the trial was already underway, I was flying a delta wing in the Hautes-Alpes region. There, a man in his thirties ran a combined shop, restaurant, and dormitory for flying enthusiasts. Incidentally, he gave flight lessons on a pendulum aircraft identical to the one that had broken in mid-air after 100 hours of...