Helicopter maintainance issues after 10000 hours
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From: swansea, wales
Helicopter maintainance issues after 10000 hours
This is a genuine question seeking answers, and I od not have an opinion one way or the other at this point.
I keep reading that public services such as the police and more recently the RAF air sea rescue sea kings are reaching or have reached the magic 10.000 hour airframe limits hence ought to be changed or upgraded to new airframes. My question si what occurs after that amount of hours to significantly change the maintainace input? I ask because I am aware of CHC and others operationg s61n's that have in excess of 40.000 airframe hours. If they can do it, why cant the sectors mentioned? If critical components have life limited lifetimes, then this does not sudenly change when the airframe they are fitted to reaches 10.000 hours?
Many thanks for any informative replies.
I keep reading that public services such as the police and more recently the RAF air sea rescue sea kings are reaching or have reached the magic 10.000 hour airframe limits hence ought to be changed or upgraded to new airframes. My question si what occurs after that amount of hours to significantly change the maintainace input? I ask because I am aware of CHC and others operationg s61n's that have in excess of 40.000 airframe hours. If they can do it, why cant the sectors mentioned? If critical components have life limited lifetimes, then this does not sudenly change when the airframe they are fitted to reaches 10.000 hours?
Many thanks for any informative replies.
Joined: Mar 2003
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From: the hills of halton
For some there is also a calender limit
"Elements of the US Army Aviation UH-60A/l Blackhawk helicopter fleet will begin reaching their sevice life goal of 25 years in 2002. In order for the fleet to remain operationally effective through the time period 2025-2030 the aircraft will need to go through an inspection, refurbishment, and modernization process that will validate the structural integrity of the airframe, incorporate improvements in sub-systems so as to reduce maintenance requirements, and modernize the mission equipment and avionics to the levels compatible with Force XXI and Army After Next (AAN) demands. A Service Life Extension Program (SLEP) is planned for the UH-60 beginning in FY99. The UH-60 modernization program will identify material requirements to effectively address known operational deficiencies to ensure the Black Hawk is equipped and capable of meeting battlefield requirements through the 2025-2030 timeframe. Primary modernization areas for consideration are: increased lift, advanced avionics (digital communications and navigation suites), enhanced aircraft survivability equipment (ASE), increased reliability and maintainability (R & M), airframe service life extension (SLEP), and reduced operations and support (O & S) costs. Suspense date for the approved Operational Requirements Document (ORD) is December 1998. "
Federation of American Scientists :: UH-60 Black Hawk, UH-60L Black Hawk, UH-60Q MEDEVAC, MH-60G Pave Hawk, HH-60G Pave Hawk, CH-60 Sea Hawk
The fact that many manufacturers have a 10,000 hr inspection would suggest that they expect the airframe to last longer than that.
I see many references to airframes designed for 10,000 hr minimum life , maybe they have money burning a hole in their pocket that they need to justify spending.
"Elements of the US Army Aviation UH-60A/l Blackhawk helicopter fleet will begin reaching their sevice life goal of 25 years in 2002. In order for the fleet to remain operationally effective through the time period 2025-2030 the aircraft will need to go through an inspection, refurbishment, and modernization process that will validate the structural integrity of the airframe, incorporate improvements in sub-systems so as to reduce maintenance requirements, and modernize the mission equipment and avionics to the levels compatible with Force XXI and Army After Next (AAN) demands. A Service Life Extension Program (SLEP) is planned for the UH-60 beginning in FY99. The UH-60 modernization program will identify material requirements to effectively address known operational deficiencies to ensure the Black Hawk is equipped and capable of meeting battlefield requirements through the 2025-2030 timeframe. Primary modernization areas for consideration are: increased lift, advanced avionics (digital communications and navigation suites), enhanced aircraft survivability equipment (ASE), increased reliability and maintainability (R & M), airframe service life extension (SLEP), and reduced operations and support (O & S) costs. Suspense date for the approved Operational Requirements Document (ORD) is December 1998. "
Federation of American Scientists :: UH-60 Black Hawk, UH-60L Black Hawk, UH-60Q MEDEVAC, MH-60G Pave Hawk, HH-60G Pave Hawk, CH-60 Sea Hawk
The fact that many manufacturers have a 10,000 hr inspection would suggest that they expect the airframe to last longer than that.
I see many references to airframes designed for 10,000 hr minimum life , maybe they have money burning a hole in their pocket that they need to justify spending.
Thread Starter
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From: swansea, wales
thanks for that, I can see where the airframe and perhaps updates to electronics that would be presumeably be readily available on new builds might prompt retirement of an older airframe on economic grounds.
Joined: May 2001
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From: Escrick York england
In the uk the tax rules give a tax break at 10,000 hours
any aircaft used by police and med cease to become long term assets and write downs are taxed differenly
this maybe what they are refering too
any aircaft used by police and med cease to become long term assets and write downs are taxed differenly
this maybe what they are refering too
Thread Starter
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From: swansea, wales
perhaps it is something like that driving decisions to replace older machines. I am no mechanic but wondered if there was something inherent in a machine where they suddenly become more maintainance intensive after that landmark was passed. Thanks for the replies.
Joined: Mar 2004
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From: Indonesia
In my experience the figure of ten thousand hours does not mean much and I work on a standard Bell medium twin civilian operations. Owning and maintaining a helicopter is like owning a 1910 Rolls Royce, you maintain to the approved maintenance schedule. Change the bits when due and be just as observant as when the machine was younger. That may be an over simplification and some types of helicopters or ones that did logging will have bits work loose or cracks. Find them and fix them.
Joined: Jul 2000
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From: Toledo, OH
There are many helicopters out there that are well over 10,000 hours. As long as the proper maintenance is done, there really isn't any major issue with it. High time airframes generally have different problems than low time airframes. If they are high time they are generally being 'rode hard and put away wet' so to speak. If you want to talk about high time aircraft, lets talk airliners. They generally fly 3000+ hours a year. It is not unusual to see B747 Classics with well over 100,000 hours. Some of the better flying aircraft I have flown have been high time aircraft. All the rough spots have been smoothed down and the kinks worked out.
A lot of this high time concern goes back to the early days of the 707, when the UK put a life limit on the 707 of 55,000 hours. They removed it when Pan Am showed them that doing proper phase and preventative maintenance could extend the useful life of the aircraft.
Generally, I have more concerns about an aircraft that has an exceptionally low flight time for its age. In my experience, you generally have more problems with them, as they tend to go long periods of not flying.
A lot of this high time concern goes back to the early days of the 707, when the UK put a life limit on the 707 of 55,000 hours. They removed it when Pan Am showed them that doing proper phase and preventative maintenance could extend the useful life of the aircraft.
Generally, I have more concerns about an aircraft that has an exceptionally low flight time for its age. In my experience, you generally have more problems with them, as they tend to go long periods of not flying.
Joined: Jun 2002
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From: Anywhere
Northumbria has/had an EC135T1 that passed 10,000 hrs a few yrs ago, its still working in the Police role for Cleveland and is only being replaced because the CAA have dictated that all Police A/C need to SPIFR.
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From: US
I'd sure like to see the Miner's Rule equation that came up with that "magic" 10,000 hours.
"Hard Time" maintenance schedules have been the norm since the advent of helicopter aviation. That is changing with Condition Based Maintenance (CBM) concepts in conjunction with Health and Usage Monitoring Systems (HUMS). A google search will provide much information on the above.
FYI, first time poster, long time lurker. Great forum! 27 years of (US Military) helicopter flight and maintenance experience.
"Hard Time" maintenance schedules have been the norm since the advent of helicopter aviation. That is changing with Condition Based Maintenance (CBM) concepts in conjunction with Health and Usage Monitoring Systems (HUMS). A google search will provide much information on the above.
FYI, first time poster, long time lurker. Great forum! 27 years of (US Military) helicopter flight and maintenance experience.
Joined: Jan 2006
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From: 3nm SE of TNT, UK
Timex,
Happy to be corrected but I think you will find that the CAA have directed that all Public Transport aircraft must have an autopilot height and heading hold facility for all flights at night. They are not just picking on the police.
Happy to be corrected but I think you will find that the CAA have directed that all Public Transport aircraft must have an autopilot height and heading hold facility for all flights at night. They are not just picking on the police.
Joined: Apr 2008
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From: Europe
Bolkow,
As some other poster said: the 10 000 hour number is, regarding maintenance, nothing special. I wrote maintenance programs for several helicopter types and never came across anything special with this hours. (Well, Jet ranger has servoactuator support frame with 10 000 hours life limit)
Helicopters, apart from modern big jets, still rely heavily on "hard limit" system where critical parts are thrown away after certain service time, meaning, that an old airframe, having 30 000 hours, has critical parts replaced several times in between.
My company is operating 30 years old 212, that looks great, bcouse there was a lot of money invested in it thru the time. (but 30 years ago no one complained about noise or bumpy, slow ride or fuel spitting at shutdown, which is today less and less tolerated)
Problems with old machines are different - things that might never be replaced start causing problems like wiring (brittle insulation, etc.), hard tubing (cracks, chaffing in some hidden areas etc.) But the biggest problem might become parts availability and/or component repair capability. Just received an offer from manufacturer, where lead time for T/R drive couplings was more than a year!!!
hoistop
As some other poster said: the 10 000 hour number is, regarding maintenance, nothing special. I wrote maintenance programs for several helicopter types and never came across anything special with this hours. (Well, Jet ranger has servoactuator support frame with 10 000 hours life limit)
Helicopters, apart from modern big jets, still rely heavily on "hard limit" system where critical parts are thrown away after certain service time, meaning, that an old airframe, having 30 000 hours, has critical parts replaced several times in between.
My company is operating 30 years old 212, that looks great, bcouse there was a lot of money invested in it thru the time. (but 30 years ago no one complained about noise or bumpy, slow ride or fuel spitting at shutdown, which is today less and less tolerated)
Problems with old machines are different - things that might never be replaced start causing problems like wiring (brittle insulation, etc.), hard tubing (cracks, chaffing in some hidden areas etc.) But the biggest problem might become parts availability and/or component repair capability. Just received an offer from manufacturer, where lead time for T/R drive couplings was more than a year!!!
hoistop
Joined: Feb 2004
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From: Langley, B.C. Canada
Hours are only "part" of the equation......"CYCLES", will be a "huge" part of what an airframe may survive????
Whether a 737 has 40,000 hours airtime, pales by comparison to 160,000 cycles, for a takeoff and landing !
We have "Cranes" that have logged over 50,000 hours......but the cycles of a "lift and landing" are almost beyond a mathematical equation (ie: hard landing/ overtorque) ????
My point is.......the company operating an aircraft should "know", the weaknesses of "said aircraft"......and have the maintenance department carry out the inspections and work required, to keep the aircraft "airworthy" (SAFE) !!!!!
At the end of any work day......the only thing that is important, is the "flight crew go home safe and sound" !!
Whether a 737 has 40,000 hours airtime, pales by comparison to 160,000 cycles, for a takeoff and landing !
We have "Cranes" that have logged over 50,000 hours......but the cycles of a "lift and landing" are almost beyond a mathematical equation (ie: hard landing/ overtorque) ????
My point is.......the company operating an aircraft should "know", the weaknesses of "said aircraft"......and have the maintenance department carry out the inspections and work required, to keep the aircraft "airworthy" (SAFE) !!!!!
At the end of any work day......the only thing that is important, is the "flight crew go home safe and sound" !!
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From: Land of the Angles
Bolkow
Thinking Military airframe limitations verses Civil.....
When non-standard items or systems are added to Military platforms in particular, but also likely to include police helicopters as well for mission requirements, such equipment may require its own testing and approval. In these cases a RFM Supplement may be required for incorporation into the basic RFM. Depending on the type and location of the equipment, this supplement may impose restrictions beyond the normal Operating Limitations.
In addition to this, certain Military helicopters have been designed and tested to operating limitations different from those approved in the standard commercial RFM. Due to its requirement to operate in hostile environments, a military variant of the commercial platform that has been approved by the OEM to perform specific manoeuvres that are outside of standard commercial limits. Military platforms therefore have their own Rotorcraft Flight Manual and maintenance manuals, and accordingly, its own “Airworthiness Limitations and Inspection Requirements” ALIR that defines component retirement and overhaul life limits that may be reduced from the commercial standard.
Thinking Military airframe limitations verses Civil.....
When non-standard items or systems are added to Military platforms in particular, but also likely to include police helicopters as well for mission requirements, such equipment may require its own testing and approval. In these cases a RFM Supplement may be required for incorporation into the basic RFM. Depending on the type and location of the equipment, this supplement may impose restrictions beyond the normal Operating Limitations.
In addition to this, certain Military helicopters have been designed and tested to operating limitations different from those approved in the standard commercial RFM. Due to its requirement to operate in hostile environments, a military variant of the commercial platform that has been approved by the OEM to perform specific manoeuvres that are outside of standard commercial limits. Military platforms therefore have their own Rotorcraft Flight Manual and maintenance manuals, and accordingly, its own “Airworthiness Limitations and Inspection Requirements” ALIR that defines component retirement and overhaul life limits that may be reduced from the commercial standard.
Joined: Dec 2006
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From: Bury St. Edmunds
Bolkow
Another factor is the time spent getting to 10,000 hrs. In the civil world no utilisation means no business = no profits. Therefore, hours per day might be 7 or more - say 40-50 hours per week. ERGO 10,000 hours could be reached 4 to 5 years!
Contrast this with a military helo on SAR standby. It might do 10 hours for crew continuity training and say another 2-4 hours per week on a "shout". Hours then accrue at a quarter the rate of a civil operator. Result, military helo might be 16 - 20 years old at 10,000hrs by which time spare parts and support may be both costly and limited. Avionics too will be obsolete, ever try getting a new auto pilot/radar/radio 15 years after they ceased being made....
All valid reasons for looking at a new(er) machine, not to mention it might have more appeal to the pax in the same way as you might choose the newest rental car/taxi available when needing one when you arrive at the airport. What's the average age of Easyjet's fleet, about 3 years? Must improve EJ's dispatch rate and improve their customer appeal, not to mention fuel burn all of which they wouldn't have done for good commercial reasons.
MB
Another factor is the time spent getting to 10,000 hrs. In the civil world no utilisation means no business = no profits. Therefore, hours per day might be 7 or more - say 40-50 hours per week. ERGO 10,000 hours could be reached 4 to 5 years!
Contrast this with a military helo on SAR standby. It might do 10 hours for crew continuity training and say another 2-4 hours per week on a "shout". Hours then accrue at a quarter the rate of a civil operator. Result, military helo might be 16 - 20 years old at 10,000hrs by which time spare parts and support may be both costly and limited. Avionics too will be obsolete, ever try getting a new auto pilot/radar/radio 15 years after they ceased being made....
All valid reasons for looking at a new(er) machine, not to mention it might have more appeal to the pax in the same way as you might choose the newest rental car/taxi available when needing one when you arrive at the airport. What's the average age of Easyjet's fleet, about 3 years? Must improve EJ's dispatch rate and improve their customer appeal, not to mention fuel burn all of which they wouldn't have done for good commercial reasons.
MB
Joined: Jun 2007
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From: Out of my suitcase
Hi Bolkow,
Working for Heli-One, MRO provider for CHC and third party customers let me add the following.
A helicopter is just basically frame filled with a hand full of replaceable parts. So all the parts have their own limits and can be taken out of the “airframe time limits”
On some Militairy helicopters such an “airframe time limit” is known, for instance the Westland lynx has an airframe limit of 7000 hours. After that you need to throw away the aircraft. Currently some users have an extension till 8000 flight hours. Other operators have even reframed the helicopters when it reached 7000 flight hours, buying new frames and installing the old components. It could be that Westland put such a limit also on the Seaking airframes. These time limits are not so strange if you think that the Seaking and Lynx are helicopter originally designed to serve for 15 to 20 years and should have never reached these kind of flight hours.
Within the civil helicopter business (medium and heavy twin) I am not aware of 1 helicopter with an “airframe time limit”. We are known with heavy maintenance check, like G-Check and overhauls.
For an S61 it used to be at 10000 hours but has been increased up to 12500 (based on escalation of previous G-checks). After these hours you perform a huge airframe inspection (corrosion, cracks etc), rebuild the aircraft repaint if necessary and continue to fly.
The Super Puma has a similar inspection at 7000 flight hours or 10 years whatever comes first. In the reality is that Militairy organizations fly about 200hrs a year per aircraft, were commercial operators fly about 2000 flight hours per year.
This means that a commercial aircraft will see a G-check every 3 to 4 years based on the hour limit were the Militairy aircraft will see a G-check every 10 hours based on the calendar limit.
Cost wise these kind of G-checks will start around with a 7 figure number and will go up if the condition of the aircraft is poor. You can imagine that a Militairy aircraft flying over sea will have more corrosion issues during a G-check (after 10 years) then a commercial aircraft after 4 years.
From my own experience the S61 is one of the best airframes build ever, aircraft with more than 40000 flight hours are still in very good shape and easily pass the G-checks. So you are correct from a technical point of view there is no reason to ground the aircraft.
So basically it can be one of the following reasons:
1) Westland put a “airframe time limit on the frame” this cannot be ignored by the operator, so the need to ground the aircraft.
2) It is not financially attractive to perform a G-check, knowing the aircraft will go out of service within a view years.
However if they would like to have the G-check performed, we as Heli-One would very much like to offer our services!
Mark
Working for Heli-One, MRO provider for CHC and third party customers let me add the following.
A helicopter is just basically frame filled with a hand full of replaceable parts. So all the parts have their own limits and can be taken out of the “airframe time limits”
On some Militairy helicopters such an “airframe time limit” is known, for instance the Westland lynx has an airframe limit of 7000 hours. After that you need to throw away the aircraft. Currently some users have an extension till 8000 flight hours. Other operators have even reframed the helicopters when it reached 7000 flight hours, buying new frames and installing the old components. It could be that Westland put such a limit also on the Seaking airframes. These time limits are not so strange if you think that the Seaking and Lynx are helicopter originally designed to serve for 15 to 20 years and should have never reached these kind of flight hours.
Within the civil helicopter business (medium and heavy twin) I am not aware of 1 helicopter with an “airframe time limit”. We are known with heavy maintenance check, like G-Check and overhauls.
For an S61 it used to be at 10000 hours but has been increased up to 12500 (based on escalation of previous G-checks). After these hours you perform a huge airframe inspection (corrosion, cracks etc), rebuild the aircraft repaint if necessary and continue to fly.
The Super Puma has a similar inspection at 7000 flight hours or 10 years whatever comes first. In the reality is that Militairy organizations fly about 200hrs a year per aircraft, were commercial operators fly about 2000 flight hours per year.
This means that a commercial aircraft will see a G-check every 3 to 4 years based on the hour limit were the Militairy aircraft will see a G-check every 10 hours based on the calendar limit.
Cost wise these kind of G-checks will start around with a 7 figure number and will go up if the condition of the aircraft is poor. You can imagine that a Militairy aircraft flying over sea will have more corrosion issues during a G-check (after 10 years) then a commercial aircraft after 4 years.
From my own experience the S61 is one of the best airframes build ever, aircraft with more than 40000 flight hours are still in very good shape and easily pass the G-checks. So you are correct from a technical point of view there is no reason to ground the aircraft.
So basically it can be one of the following reasons:
1) Westland put a “airframe time limit on the frame” this cannot be ignored by the operator, so the need to ground the aircraft.
2) It is not financially attractive to perform a G-check, knowing the aircraft will go out of service within a view years.
However if they would like to have the G-check performed, we as Heli-One would very much like to offer our services!
Mark
Thread Starter
Joined: Dec 2006
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From: swansea, wales
I guess what raised the question for me in particular was the issue of older Canadian coastguard sea kings. As I understand it the aircraft are all still flying, but their maintainance hours proportional to their flying hours has increased dramatically, like 7 maintaince hours per flying hour whereas a newer a/c would have much lower maintainace hours per flight hour. The puzzlew for me is what exactly are these maintainance ohurs being expended on, and why have the same items at this stage begun to need such increased maintainance if they are lifed items? Maybe its the airframe?
Thread Starter
Joined: Dec 2006
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From: swansea, wales
Mark H1, a sincere thank you for the time you spent giving me that very informative reply, it goes a long way towards answering the puzzling questions I have particularly in relartion to the canadian sea kings. I guess their maintainance has increased in precisley the area of airframes as opposed to the life limited part contained within. Thank you very much.
