To: arcniz
I am enclosing the following in order to shed some light on how Airbus and their vendors do business. I will state that the information following deals with theA-310 and the A-320 but since the major players are basically the same the A-300 can be tarred with the same brush.
I worked as the senior Reliability and Maintainability engineer on the A-310. I worked on a consulting contract at Liebherr Aerotechnik in Lindenberg, Germany. Liebherr was the senior contractor in the design of the secondary flight control system power drives and actuators. They were also senior contractor in the design of the flap / slat computer which was designed and built by Marconi in the UK. The integrating contractor was MBB-Erno based in Bremen, Germany. The lead in the wing design was BAe in Hatfield in the UK. Our associate contractor in the design of the power drives and the actuators was Lucas Aerospace in Wolverhampton in the UK.
The story is about to unfold and it is broken into several sub stories.
1) During the tear down of a slat actuator that had been used in test and development I discovered a strange erosion pattern. I referred it to our stress engineer and he said it was stress corrosion. I placed the unit under high power magnification and the strange pattern turned out to be spark erosion. I could not get the stress engineer to agree. I talked to a senior design engineer and asked him to verify the continuity of the installed system on the iron bird. The check showed that the slat system was not grounded to the iron bird, which meant that when installed in the aircraft it would not be bonded to the airframe. I contacted my counterpart at Lucas and he found the same to be true for the flaps. I brought this problem to the attention of my department manager and he took it to the Vice President and the senior project engineer. To support my argument I had referenced an Airbus technical directive (TDD 20 A 001) which addressed Electrical Bonding, Lightning Strike Protection and Electrostatic Discharge. Their argument against my criticism of the design was two fold. They stated that the TDD was not fully approved and therefore did not apply to the A-310 design. Although Airbus directed in the design specification that any problems related to Reliability, Maintainability and Safety had to be brought to their attention it was Liebherrs’ position that if they brought it to the attention of Airbus they would have to absorb the cost of the design modification. They suggested that I talk to MBB-Erno, which I did. Much to my surprise they took the Liebherr position of not telling Airbus as a means of avoiding the redesign costs. I then took the problem to Bae and they told me that they were in sympathy with my problem but they could do nothing about it. This is the company that designed the wing and was responsible for flight safety and ultimate certification.
According to the Airbus TDD the two most frequent points of lightning attachment are the nose which has strike diverters and a partially extended slat. Should lightning hit the extended slat it would arc to the outboard slat actuator and into the wing structure. The way the A-310 wing is constructed the slat actuator jack screw is retracted into the wing and it is separated by a thin Titanium wall. On the other side of the Titanium wall is the outboard fuel tank, which will most likely explode when the arc occurs.
The clincher to this problem is that the TDD was eventually approved and the problem of non- electrical bonding would or, should have been detected during final inspection of the aircraft prior to flight-testing. The non-bonding of the flaps is another story. According to Lucas calculations the flaps would build up a static charge of 800-1400 volts and as the flaps retracted the voltage would arc to the wing skin or the rear of the rear spar.
2) Airbus and JAR / FAA requirements dictate that an uncommanded operation of the flaps or slats should occur no more frequently than 1 10 9 or one time in a billion hours for the fleet. In performing the Failure modes Effects Analysis (FMEA) for the Flap and Slat Power Control Units (PCU) it was determined that if an internal leak that bypassed the control solenoids on the PCUs it could cause an uncommanded operation of the flaps or the slats depending on which PCU developed the crack. The problem was that a similar crack could also occur that would cause faulty operation of the PCU or it could result in a loss of a single hydraulic system. The predicted occurrence of this type of crack is .1 10 6 or, one time in 10 million hours of fleet operation. We were forced to show that the crack occurrence was 1 10 9 and not .1 10 6 which is the difference between 10,000,000 hours and 1,000,000,000 hours which was not realistic. We ended up doing it over my objections in order to show we met the safety requirements dictated by the certification authorities.
During the life cycle testing of the slat system Liebherr encountered a runaway slat system and the flap slat computer was not only unable to detect it was unable to stop it. This would be a minor problem on the slat system regarding uncommanded extension, as the air loads at cruise would keep them retracted. However if it occurred on the slat system causing an uncommanded retraction during takeoff it could cause major or catastrophic problems. The same is true if it happened on the flap system. Again Liebherr was required to notify Airbus about the runaway as well as the computer being oblivious to the problem. They didn’t notify Airbus. Instead, they contacted Lufthansa and Swiss Air, which had 17 Airbus A-310s in service. Liebherr made a quick fix and told the operators to notify them when they had an aircraft on ground over night and Liebherr would install a “more reliable” designed PCU at no cost. When Liebherr encountered the problem the accelerated test had about 1800 hours of operation and the operating aircraft were fast approaching that number.
3) The flap slat computer was designed and built by Marconi. I had several encounters with Marconi on other programs and I found them extremely difficult to deal with. The same was true for the A-310 program. Per Airbus program requirements I directed Marconi to analyze the failure of every piece part in the computer and indicate how the failure manifested itself when the part failed. Marconi replied that it would be too expensive to do that so instead they just indicated the failure rate of each part and combined it in order to show the total failure rate for the computer. This proved to be totally insufficient to meet the Airbus requirements, as it did not reflect a true FMEA.
Marconi had a running battle with Lucas Aerospace accusing them of robbing trade secrets and stealing their top designers. Lucas like Liebherr constructed an iron bird to test and develop the flap drive system. Marconi provided Liebherr a complete brass board of the computer that had the total capability to control the slat system and diagnose any system problems. Despite this requirement the computer was unable to respond to the runaway slat system on the Liebherr iron bird. Instead of providing Lucas with a similar brassboard computer they provide one lane of the computer or 1/4th of the computer. This allowed the extension and retraction of the flap system without having any diagnostic capability. Without this diagnostic capability Lucas could not adequately test the system and therefore, they could not certify the system. The system ultimately received certification although it was not properly tested.
On the first revenue flight for Lufthansa they flew from Frankfurt to Cairo. Upon landing the pilots could not retract the flaps. No one including the computer was able to diagnose the problem and the computer did not recognize that a problem had occurred. The aircraft was returned to Frankfurt in non-revenue service with the flaps fully extended. Upon its’ return the same situation existed. Nobody could figure out what was wrong. The flaps were mechanically disconnected and hand cranked in. The system was reconnected and everything worked OK.
Marconi also stated that on the A-320 when Lucas was going to be the lead design contractor Marconi would not work with them and most likely not bid on the contract. I do not know if they followed through with their threat.
4) I concluded that I had done everything possible to bring the problems to the attention of everyone in the chain of command with the exception of Airbus and to do so would place my position in jeopardy. After leaving that consulting position I went to another in Italy on helicopters. While on that assignment I discovered that the A-310 had been certificated in the USA. I sent a letter to the FAA explaining everything. Two months later I received a letter thanking me and telling me that they would bring the problem to the attention of the DGCA. Four months later I received a letter from the FAA stating that the DGCA had indicated that the problems were corrected. I contacted a friend still at Liebherr and he said that nothing had changed. I sent a more forceful letter to the FAA stating that I had absolved myself of any responsibility and if something happened they could be brought into any litigation resulting from a crash. They eventually took action and the Vice President and the senior program manager were fired but nothing was done to correct the design. All of the problems I described above are waiting in the wings (pun intended) and will manifest themselves sometime in the future. It should be noted that an A-320 from Air Canada suffered an uncommanded retraction of the flaps during takeoff and the computer could not stop it.
4) On December 17, 1997 Airbus Industrie issued Airworthiness Directive 90-092-109(B)R3 which dealt with the inspection of the Vespel Bushes in the Flap / Slat Transmission-Universal Joint Assemblies. One of the checks was to determine if there was electrical continuity in the bushes they were to be replaced if continuity was discovered. When the system was designed the bushes which were called Rose Bushes were impregnated with carbon to make them electrically conductive. I do not believe the design was changed to remove the Rose Bushes. What I do believe is that the English translation got it wrong. I contacted the DGCA, the FAA and the Canadian MOT and never got any feedback on the possibility of a mis-translation. I contacted both the FAA and the Canadian MOT telling them that their respective versions of the Airbus AD were not in agreement and that their respective translations from the French original might be wrong. I also contacted the DGCA telling them that there was a possibility that the two translations were not correct. I never heard from any of them regarding this potential conflict.
To: arcniz
I had to delete this part of my post above in order to comply with the maximum character requirements for posts.
I have been banned from Rotorheads for speaking the truth, which was interpreted as libel by the moderators. The following is 100% true and I can back everything up as being true. You speak of reliability as if it were some means of assuring that airplanes are safe. The following will show you how reliability really works in the aircraft industry. I was going to disguise the names of the participants but since my statements are already entered into the files of the FAA, the DGCA and the LBA and the RAI I’ll let it stand. I'll wait to see if the moderators agree.