Cessna Sovereign - investigation identifies big airworthiness problem
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Cessna Sovereign - investigation identifies big airworthiness problem
http://www.aaib.gov.uk/cms_resources...0%20G-CJCC.pdf
How did this get past the certifying authority?
A huge own goal by a big manufacturer. Are any other types similarly configured, I wonder? (None of the little Cessna jets we have are...).
How did this get past the certifying authority?
A huge own goal by a big manufacturer. Are any other types similarly configured, I wonder? (None of the little Cessna jets we have are...).
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We covered this last recurrent, the x flow valve is opened with the left bus and closed with the right.
Cant quite remember what the circumstances were exactly (wrote them in our checklist to avoid ) but there was a combination of button presses that with one side in emer and a fuel pump selected on and x flow selected prior to going to emer. We managed to get an engine to flame out.....
At the time we thought it was a sim thing, FSI chap wrote to the sim techs and Cessna. Maybe its not a sim thing and I need to publish the details here.....
The general consensus was that it would never have been certified like that....would it?
Edit to say knowing the 680 it'll be a logic board swap out nothing major I would say.
Whos operating CC now is it the eurojet machine or bookajet
Cant quite remember what the circumstances were exactly (wrote them in our checklist to avoid ) but there was a combination of button presses that with one side in emer and a fuel pump selected on and x flow selected prior to going to emer. We managed to get an engine to flame out.....
At the time we thought it was a sim thing, FSI chap wrote to the sim techs and Cessna. Maybe its not a sim thing and I need to publish the details here.....
The general consensus was that it would never have been certified like that....would it?
Edit to say knowing the 680 it'll be a logic board swap out nothing major I would say.
Whos operating CC now is it the eurojet machine or bookajet
Last edited by G-SPOTs Lost; 8th Oct 2010 at 22:38.
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Bookajet are selling now G-CJCC with its "nightclub interior" on avinode, not sure whether is on their AOC..........
Eurojet are looking after sales on G-CPRR temporarily whilst Twinjet wait to have it listed on their AOC
Eurojet are looking after sales on G-CPRR temporarily whilst Twinjet wait to have it listed on their AOC
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The report makes interesting reading. It seems that it also happens to happens to the Citation X, which could have rather wide reaching implications should the decision is made to ground the worldwide fleet until they have fixed it.
I'm a little suprised that this has been discovered in a sim session as illuded to by G-Spot's Lost and Cessna appear to have not done anything about it. In any case a massive bol*ock drop by Cessna.
The only commercial Sovereigns in the UK are CJCC and SIRJ, both operated by Bookajet and CPRR operated on Eurojet's AOC but powered by Twinjet. I would be interested to know if any operators of the Citation X/Sovereign have taken any precautionary measures /tried their own aircraft on the ground to see if their aircraft does it. Obviously a slightly worrying prospect if an aircraft can be operated completely in line with SOP's and still end up with a massive fuel imbalance - even though it was still controllable.
I'm a little suprised that this has been discovered in a sim session as illuded to by G-Spot's Lost and Cessna appear to have not done anything about it. In any case a massive bol*ock drop by Cessna.
The only commercial Sovereigns in the UK are CJCC and SIRJ, both operated by Bookajet and CPRR operated on Eurojet's AOC but powered by Twinjet. I would be interested to know if any operators of the Citation X/Sovereign have taken any precautionary measures /tried their own aircraft on the ground to see if their aircraft does it. Obviously a slightly worrying prospect if an aircraft can be operated completely in line with SOP's and still end up with a massive fuel imbalance - even though it was still controllable.
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The most worrying aspect is that these are long range aircraft. Yes, the incident aircraft landed safely... Had it been further from a suitable airport - and even the middle of Biscay might have been enough - it seems almost certain that control would have been lost during approach, and the aircraft lost.
I'm genuinely astonished that airworthiness action has not yet been taken.
It's clear that these aircraft do not meet the relevant standards and should not fly.
I think it is very important that any relevant evidence should be handed to the investigators. In particular, those involved in the simulator event should send their accounts to the UK AIB as soon as they can (contact details on the bulletin I posted a link to).
The notion that there might have been a cover-up of a known problem of this magnitude, and one which springs from simply incompetent design, is deeply disturbing.
Later, someone will have to work out how the certification process fell over. I'm wondering what problems lie dormant on our aircraft... Some modifications to electrical systems have already proven below par, though their effects were not so dramatic...
I'm genuinely astonished that airworthiness action has not yet been taken.
It's clear that these aircraft do not meet the relevant standards and should not fly.
I think it is very important that any relevant evidence should be handed to the investigators. In particular, those involved in the simulator event should send their accounts to the UK AIB as soon as they can (contact details on the bulletin I posted a link to).
The notion that there might have been a cover-up of a known problem of this magnitude, and one which springs from simply incompetent design, is deeply disturbing.
Later, someone will have to work out how the certification process fell over. I'm wondering what problems lie dormant on our aircraft... Some modifications to electrical systems have already proven below par, though their effects were not so dramatic...
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Hang on chaps, its two aircraft out of a fleet of 300.
We MOR'd an incident we had with out aircraft after the terminals were reversed on our two fire bottles, Im guessing its not an architecture issue probably one of wichita's finest farmboys getting his pluses and his minuses mixed up on a limited number of aircraft. Be interested to know the serial numbers of the aircraft they checked
Im not a Cesnna fanboy by any means but there'll be an SB/ inspection and a repair kit manufactured and sent out and a few red faces getting fired at ICT.
I'll try mine on Monday and see if it happens, I'll also try the flame out "procedure" for real and see what happens although you never know with the Sovereign whether the WoW logic will affect it.
I'll post up here what the issue was with the "flame out" so others can be aware soon as I get to my emer chklist Monday
We MOR'd an incident we had with out aircraft after the terminals were reversed on our two fire bottles, Im guessing its not an architecture issue probably one of wichita's finest farmboys getting his pluses and his minuses mixed up on a limited number of aircraft. Be interested to know the serial numbers of the aircraft they checked
Im not a Cesnna fanboy by any means but there'll be an SB/ inspection and a repair kit manufactured and sent out and a few red faces getting fired at ICT.
I'll try mine on Monday and see if it happens, I'll also try the flame out "procedure" for real and see what happens although you never know with the Sovereign whether the WoW logic will affect it.
I'll post up here what the issue was with the "flame out" so others can be aware soon as I get to my emer chklist Monday
Not knowing the aircraft systems,but having read the AAIB report,could anyone elaborate if left/right systems are `mirrored`,and similar problem `may` happen to the right system,as there is no mention of trying that as well ?
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G-SPOT, my understanding is that this is a design issue, not a rogue aircraft from the production line. Discussion over a glass of wine with a colleague rated (though not currently) on the 680 suggests that the mirror failure has different consequences.
A word of caution: the first rule of flight test is: never poke sticks at an aircraft. Mucking about to look at a problem, either on the ground or in the air, could have unintended and unwelcome consequences. My advice would be not to fly the aircraft until there's a definitive answer from the Feds.
A word of caution: the first rule of flight test is: never poke sticks at an aircraft. Mucking about to look at a problem, either on the ground or in the air, could have unintended and unwelcome consequences. My advice would be not to fly the aircraft until there's a definitive answer from the Feds.
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There is another thing that bothers me, cause its not the first time something like it happens on a Sov:
G-SPOT, how will you try it?
Both engines running, ELEC to emer, select GEN off, bus tie closed, see what happens ?
My next trip is tonight...
When the aircraft was powered up again, all systems appeared to operate normally,
I'll try mine on Monday and see if it happens
My next trip is tonight...
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A word of caution: the first rule of flight test is: never poke sticks at an aircraft. Mucking about to look at a problem, either on the ground or in the air, could have unintended and unwelcome consequences. My advice would be not to fly the aircraft until there's a definitive answer from the Feds.
As mentioned above the X flow valve which is the problem in both cases is powered closed and opened by different sides. From memory the flameout issue was caused by the logic closing the motive flow valve on one side when x-feeding but the logic not being able to close it again due to the power to the valve being lost to close it, you then had both boost pumps opposing each other and the engine stopped.
The worst checklist procedure is the isolation of an electrical problem on on of the buses on the C680, its not automated and runs to two pages it was during this proc that we dscovered it (on the sim software)
The logic also controls the boost pumps automatically due to low pressure in supply, problem being in that in most of the 500's,525's,XL's putting the boost pump to off means OFF, on the 680 you have ON and NORM where the logic has total control .....the breaker for them is in the baggage bay
Edit
HD Good Luck! I'll try it tomorrow on the ramp and follow the findings in the AAIB report.
Did you go Phase V on the software yet? Any issues
Last edited by G-SPOTs Lost; 10th Oct 2010 at 10:19.
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We are indeed Phase V now, there are no real issues. If you have the charts and maps option, you´ll probably find (not all airframes are affected, thats what Cessna says anyway) that the loading process is interrupted and can´t be finished. You´d pull your PMCIA card, put the required files onto that in your computer, then load the charts and maps without the PCMCIA card in its slot and put it back in the aircraft after powering down. Power up again and your good to go.
Thats info I got from a Honeywell tech rep:
The overspeed issue is gone, works now as advertised.
Published holdings are now in the database.
You can´t go to preview if you have selected an approach other than ILS.
The ILS freq/front course selection does not work consistantly.
Apparently there are more than 300 bugs fixed, however I can't tell the difference.
Ah and the cursor goes to 1/2 rather than the radio window, so accidentaley pushing the enter knob on the CCD won´t change freqs anymore. I´d rather liked to have a beep, but Cessna incorperated that only for the datalink VHF. But that can be turned off.
Finally the ALT Alert beep is set to a lower setting, thanks for that.
Thats info I got from a Honeywell tech rep:
I wanted to share some problems seen during Phase V upgrades (SB attached) and loading the CHART CD (blue) on aircraft in operation:
1) In the SB step 19 L the file will be created but it will NOT load. Loading should then be performed using the CMC RT (instead of the APM Tool)
2) If an aircraft has Charts and an update is required, the normal loading process will not work anymore (CD in DMU). Therefore,
• you need to load the AFGS and CMC from the laptop CD drive. Note: loading the AFGS the first time might fail.
• load the PCMCIA card by:
Insert PCMCIA card into computer.
Quick Format card (don’t know if it matters but I did it)
Copy and paste these files from the Blue CD into the root of the PCMCIA card. (located in the CHARTS_DATA folder on Blue CD)
charts.bin
charts.ini
crcfiles.txt
Make sure files are NOT Read only !
Put PCMCIA back into DMU and should work.
1) In the SB step 19 L the file will be created but it will NOT load. Loading should then be performed using the CMC RT (instead of the APM Tool)
2) If an aircraft has Charts and an update is required, the normal loading process will not work anymore (CD in DMU). Therefore,
• you need to load the AFGS and CMC from the laptop CD drive. Note: loading the AFGS the first time might fail.
• load the PCMCIA card by:
Insert PCMCIA card into computer.
Quick Format card (don’t know if it matters but I did it)
Copy and paste these files from the Blue CD into the root of the PCMCIA card. (located in the CHARTS_DATA folder on Blue CD)
charts.bin
charts.ini
crcfiles.txt
Make sure files are NOT Read only !
Put PCMCIA back into DMU and should work.
Published holdings are now in the database.
You can´t go to preview if you have selected an approach other than ILS.
The ILS freq/front course selection does not work consistantly.
Apparently there are more than 300 bugs fixed, however I can't tell the difference.
Ah and the cursor goes to 1/2 rather than the radio window, so accidentaley pushing the enter knob on the CCD won´t change freqs anymore. I´d rather liked to have a beep, but Cessna incorperated that only for the datalink VHF. But that can be turned off.
Finally the ALT Alert beep is set to a lower setting, thanks for that.
Last edited by His dudeness; 10th Oct 2010 at 12:00.
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Cessnas Information on the Subject:
Cessna Sovereign - Uncommanded Fuel Transfer
Operating with the L ELEC button in EMER and the left generator off, with the right side bus/generator operating normally, can initiate an unintended transfer of fuel from the right fuel tank to the left tank. This can occur automatically during certain malfunctions or by pilot selection in response to AFM procedures. The potential for this to occur is indicated in flight by amber DC EMER BUS L and DC GEN OFF L CAS messages accompanied by cyan FUEL CROSS FEED and FUEL BOOST PUMP ON R CAS messages. If these are observed in flight, the resulting fuel imbalance may be minimized by turning the FUEL CROSSFEED selector to the OFF position and then pulling the R FUEL BOOST circuit breaker in the copilot’s circuit breaker panel in the cockpit.
A Citation Sovereign recently experienced an amber DC EMER BUS L CAS message during flight indicating that the left electrical bus isolation relay had automatically opened. When not accompanied by an excessive battery current, the AFM procedure for this message requires switching the left generator off. When this is done, all systems on the left main electrical bus will lose power, including the left fuel quantity indication and left fuel boost pump. During the 20-30 minute flight back to the departure airport, the crew noticed an increasing need for right aileron input to maintain level flight. After landing, when power was restored on the airplane, the fuel gauges indicated that the left fuel tank was full and the right tank had 3300 pounds remaining.
When power is removed from the left main electrical bus, the left Fuel Control Printed Circuit Board loses power. Further investigation revealed that this specific combination of events can cause an unintended fuel crossfeed command to the right Fuel Control Printed Circuit Board which then outputs commands to open the fuel crossfeed valve and turn on the right fuel boost pump. However, without power to the left Fuel Control Printed Circuit Board, the left motive flow valve will not close as it normally would during a right tank to left engine cross feed. Fuel will now be supplied to both engines from the right tank but, with the left motive flow valve open, motive flow fuel from the left engine will be returned to the left tank causing an increase in fuel quantity. An amber FUEL MOTIVE VLV FAIL L CAS message will also be observed since the left motive flow valve would normally be closed during right to left crossfeed.
Testing has shown that, in this condition, turning fuel crossfeed off and then turning the right fuel boost pump off by pulling the R FUEL BOOST circuit breaker on the copilot’s circuit breaker panel in the cockpit will allow fuel to be supplied to each engine from its respective fuel tank thereby minimizing any resulting fuel imbalance.
A similar scenario with the right electrical isolation relay opening and the right generator turned off will not cause fuel to transfer unless fuel crossfeed is already selected when the right main electrical bus loses power. However, since the position of the fuel crossfeed valve will be uncertain in this case (amber FUEL CROSS FEED TRANSIT message will be posted), the L FUEL BOOST circuit breaker in the pilot’s circuit breaker panel in the cockpit should be pulled to minimize any possible fuel imbalance.
A Temporary Change to the AFM will follow closely and a permanent resolution is in work.
Operating with the L ELEC button in EMER and the left generator off, with the right side bus/generator operating normally, can initiate an unintended transfer of fuel from the right fuel tank to the left tank. This can occur automatically during certain malfunctions or by pilot selection in response to AFM procedures. The potential for this to occur is indicated in flight by amber DC EMER BUS L and DC GEN OFF L CAS messages accompanied by cyan FUEL CROSS FEED and FUEL BOOST PUMP ON R CAS messages. If these are observed in flight, the resulting fuel imbalance may be minimized by turning the FUEL CROSSFEED selector to the OFF position and then pulling the R FUEL BOOST circuit breaker in the copilot’s circuit breaker panel in the cockpit.
A Citation Sovereign recently experienced an amber DC EMER BUS L CAS message during flight indicating that the left electrical bus isolation relay had automatically opened. When not accompanied by an excessive battery current, the AFM procedure for this message requires switching the left generator off. When this is done, all systems on the left main electrical bus will lose power, including the left fuel quantity indication and left fuel boost pump. During the 20-30 minute flight back to the departure airport, the crew noticed an increasing need for right aileron input to maintain level flight. After landing, when power was restored on the airplane, the fuel gauges indicated that the left fuel tank was full and the right tank had 3300 pounds remaining.
When power is removed from the left main electrical bus, the left Fuel Control Printed Circuit Board loses power. Further investigation revealed that this specific combination of events can cause an unintended fuel crossfeed command to the right Fuel Control Printed Circuit Board which then outputs commands to open the fuel crossfeed valve and turn on the right fuel boost pump. However, without power to the left Fuel Control Printed Circuit Board, the left motive flow valve will not close as it normally would during a right tank to left engine cross feed. Fuel will now be supplied to both engines from the right tank but, with the left motive flow valve open, motive flow fuel from the left engine will be returned to the left tank causing an increase in fuel quantity. An amber FUEL MOTIVE VLV FAIL L CAS message will also be observed since the left motive flow valve would normally be closed during right to left crossfeed.
Testing has shown that, in this condition, turning fuel crossfeed off and then turning the right fuel boost pump off by pulling the R FUEL BOOST circuit breaker on the copilot’s circuit breaker panel in the cockpit will allow fuel to be supplied to each engine from its respective fuel tank thereby minimizing any resulting fuel imbalance.
A similar scenario with the right electrical isolation relay opening and the right generator turned off will not cause fuel to transfer unless fuel crossfeed is already selected when the right main electrical bus loses power. However, since the position of the fuel crossfeed valve will be uncertain in this case (amber FUEL CROSS FEED TRANSIT message will be posted), the L FUEL BOOST circuit breaker in the pilot’s circuit breaker panel in the cockpit should be pulled to minimize any possible fuel imbalance.
A Temporary Change to the AFM will follow closely and a permanent resolution is in work.
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I'll bet the passengers wished that they had booked a Hawker for their flight to Turkey! As far as I can remember we do not have any fancy logic boards to go wrong, just switches for the pilots to flip in the rare event of a problem.
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"Mad Dog-11"
Anoyone remember the MD-11 when it started dumping fuel in the NATS 12-15 years ago?
It can all be attributed to the "2001-A space Oddessy" movie. The HAL 9000 computer ( Dave..I'm feeling much better, Dave...) has iterations out in the engineering ranks at all manufacturing firms.
I watched an MD-11 start to transfer fuel during a retract check at DFW. The Prox switches told the mgmnt system that it as airborne and out of CG. It was really cool to watch a new airliner with the wheels up while on the wing stands 'floating' on only two jacks, while the fuel transfer pumps did their work.
Once again; an engineer truly believes that a pilot will try to mess up his beautiful creation, while the pilot knows for a fact that this beast is really trying to kill the him and his crew.
It can all be attributed to the "2001-A space Oddessy" movie. The HAL 9000 computer ( Dave..I'm feeling much better, Dave...) has iterations out in the engineering ranks at all manufacturing firms.
I watched an MD-11 start to transfer fuel during a retract check at DFW. The Prox switches told the mgmnt system that it as airborne and out of CG. It was really cool to watch a new airliner with the wheels up while on the wing stands 'floating' on only two jacks, while the fuel transfer pumps did their work.
Once again; an engineer truly believes that a pilot will try to mess up his beautiful creation, while the pilot knows for a fact that this beast is really trying to kill the him and his crew.