Greetings, the DG is to have its annual inspection next week. Unless there are any hold-ups it should be back on line for the Friday.
Depending on the weekend weather and flying, we will de-rig on Sunday after flying or sooner if weather dictates. This will need a team of 6 for safety, please do help if you can. As we get nearer the weekend I'll post on the WhatsApp group when we are likely to de-rig.
During the week the wings will need to be hard wax polished and the fuselage and tailplane soft wax polished. Volunteers are welcomed, please let me know your availability during next week.
The club has a polishing machine for hard waxing, available to members who wish to prolong the life of their own glider's gel coat. You could learn how to hard wax on the DG first, instruction will be given.
Thanks everyone,
Barry L
DG505 G-CJZB Annual Inspection w/c 6th March
Moderators: Tony Brown, BarryL
Re: DG505 G-CJZB Annual Inspection w/c 6th March
We will derig after flying on Saturday, any help will be appreciated.
Thanks,
Barry
Thanks,
Barry
Re: DG505 G-CJZB Annual Inspection w/c 6th March
The Annual Inspection was completed on Saturday 18 March. The check flight also took place on 18th March and the glider is now available for regular Club use.
This year's inspection took longer than originally anticipated (the glider was off-line for nearly 2 weeks) for a number of reasons:
a) The belly tow hook needed replacement as it had reached the allowed number of launches (2000). For information, Tost, the manufacturer, specify that it should be replaced after 10,000 operations (mainly because of the expected life of the main spring), but of course we don't count operations, just launches. For a Club glider, we allow 5 operations per launch, hence the 2000 launches. The removal and replacement of the tow hook proved problematic due to a strengthening modification in the area of the hook which took place before the Club acquired the glider. Some aspects of the modification had not been done preventing normal replacement. A workaround was devised which took a long time, and many attempts, to reach a successful conclusion. All in all at least 2 days of work was needed where the expectation was a couple of hours. Thanks Barry for persevering with this; a back-breaking task!
You may be thinking, we don't use the belly hook at the Club, so why do we need to change it? The answer is that it is used just as often as the nose hook; the yellow release knob operates both hooks at the same time. When we removed the hook it was found that the main spring was partially broken. This cannot be seen with the hook in place. It demonstrates that the manufacturer's recommended change interval is there for a reason!
b) It had been noted that the front Turn & Slip (T&S) instrument was not working. On investigation, it was found to be a 28v instrument (ex military probably) running from the aircraft 12v supply. It may have worked in the past but well out of specification. A new voltage convertor module was fitted which raises the 12v supply to (nearly) 28v. This convertor is only operative when the front T&S is switched on. The check flight demonstrated that the instrument now performs as expected.
c) It has been requested for some time that the "Cruise/Climb" Vario switch on the front instrument panel be duplicated on the rear panel. After a fair amount of discussion on the options for achieving this, a scheme was devised using a push button switch and an LED on each panel. Pressing either switch toggles between the normal "Vario" mode (climb) and the "speed control" (SC) mode. If the LEDs are on, it indicates that the SC mode is active. Either pilot can now control this feature without any setting up before or during the flight. As a check that the new control circuitry is working properly, both LEDs will illuminate for 5 seconds when the Vario power is first applied - usually when the Master switch is turned on. The two modes of the Vario are depicted by small icons near the "10 up" marker on the LCD displays but these are not easy to see in sunlight hence the use of the LEDs. Design and implementation of this new feature took longer than anticipated contributing to the extended time for the Annual.
d) The fuselage was inverted to give better access to the undercarriage, main wheel and brake assembly. These are exposed to the normal rigors of the airfield (wet grass, mud, etc) and benefit from a strip down, clean and lubrication. This is the first time this extensive level of inspection has taken place since the repairs after the field landing in 2021. Turning the fuselage upside down and reversing the process afterwards is a task requiring a gang of about 8-10 people. Thanks to all those who assisted with this.
As part of the Annual, the opportunity was taken to carry out an extensive clean of the inside and outside of the glider. Barry's wife, Linda, did a great job cleaning the carpets and many of the exterior parts. Thanks Linda.
Steve Barclay carried out the unenviable task of hard waxing the wings. This helps prevent deterioration of the gel coat by filling the very fine surface cracks with wax, preventing the ingress of moisture. Steve nearly got the job done before the rotary polisher expired accompanied by smoke and a nasty smell - from the polisher, not Steve! Ian Surley came to the rescue with his own polisher. Thanks to both.
This exercise was masterminded by Barry who not only carried out most of the inspection and associated dismantling/reassembly activities, but also produced the required paperwork as evidence that the work has been done in accordance with the published plans. This is a time consuming task, much of it carried out away from the club in his own time. On behalf of the Club, thanks Barry. Thanks also to Ian Surley for assisting with some of the inspection work.
The ARC process has not yet been carried out as it is not due until later in the year. Again, Barry will undertake this work when the time comes.
A quick estimate suggests that some 20 man-days of work have been devoted to these activities at the Club, and possibly another 10 by individuals spending time at home carrying out associated work. Much of this important work goes unnoticed by many, but is vital to the smooth running of the Club.
Tim Fox
This year's inspection took longer than originally anticipated (the glider was off-line for nearly 2 weeks) for a number of reasons:
a) The belly tow hook needed replacement as it had reached the allowed number of launches (2000). For information, Tost, the manufacturer, specify that it should be replaced after 10,000 operations (mainly because of the expected life of the main spring), but of course we don't count operations, just launches. For a Club glider, we allow 5 operations per launch, hence the 2000 launches. The removal and replacement of the tow hook proved problematic due to a strengthening modification in the area of the hook which took place before the Club acquired the glider. Some aspects of the modification had not been done preventing normal replacement. A workaround was devised which took a long time, and many attempts, to reach a successful conclusion. All in all at least 2 days of work was needed where the expectation was a couple of hours. Thanks Barry for persevering with this; a back-breaking task!
You may be thinking, we don't use the belly hook at the Club, so why do we need to change it? The answer is that it is used just as often as the nose hook; the yellow release knob operates both hooks at the same time. When we removed the hook it was found that the main spring was partially broken. This cannot be seen with the hook in place. It demonstrates that the manufacturer's recommended change interval is there for a reason!
b) It had been noted that the front Turn & Slip (T&S) instrument was not working. On investigation, it was found to be a 28v instrument (ex military probably) running from the aircraft 12v supply. It may have worked in the past but well out of specification. A new voltage convertor module was fitted which raises the 12v supply to (nearly) 28v. This convertor is only operative when the front T&S is switched on. The check flight demonstrated that the instrument now performs as expected.
c) It has been requested for some time that the "Cruise/Climb" Vario switch on the front instrument panel be duplicated on the rear panel. After a fair amount of discussion on the options for achieving this, a scheme was devised using a push button switch and an LED on each panel. Pressing either switch toggles between the normal "Vario" mode (climb) and the "speed control" (SC) mode. If the LEDs are on, it indicates that the SC mode is active. Either pilot can now control this feature without any setting up before or during the flight. As a check that the new control circuitry is working properly, both LEDs will illuminate for 5 seconds when the Vario power is first applied - usually when the Master switch is turned on. The two modes of the Vario are depicted by small icons near the "10 up" marker on the LCD displays but these are not easy to see in sunlight hence the use of the LEDs. Design and implementation of this new feature took longer than anticipated contributing to the extended time for the Annual.
d) The fuselage was inverted to give better access to the undercarriage, main wheel and brake assembly. These are exposed to the normal rigors of the airfield (wet grass, mud, etc) and benefit from a strip down, clean and lubrication. This is the first time this extensive level of inspection has taken place since the repairs after the field landing in 2021. Turning the fuselage upside down and reversing the process afterwards is a task requiring a gang of about 8-10 people. Thanks to all those who assisted with this.
As part of the Annual, the opportunity was taken to carry out an extensive clean of the inside and outside of the glider. Barry's wife, Linda, did a great job cleaning the carpets and many of the exterior parts. Thanks Linda.
Steve Barclay carried out the unenviable task of hard waxing the wings. This helps prevent deterioration of the gel coat by filling the very fine surface cracks with wax, preventing the ingress of moisture. Steve nearly got the job done before the rotary polisher expired accompanied by smoke and a nasty smell - from the polisher, not Steve! Ian Surley came to the rescue with his own polisher. Thanks to both.
This exercise was masterminded by Barry who not only carried out most of the inspection and associated dismantling/reassembly activities, but also produced the required paperwork as evidence that the work has been done in accordance with the published plans. This is a time consuming task, much of it carried out away from the club in his own time. On behalf of the Club, thanks Barry. Thanks also to Ian Surley for assisting with some of the inspection work.
The ARC process has not yet been carried out as it is not due until later in the year. Again, Barry will undertake this work when the time comes.
A quick estimate suggests that some 20 man-days of work have been devoted to these activities at the Club, and possibly another 10 by individuals spending time at home carrying out associated work. Much of this important work goes unnoticed by many, but is vital to the smooth running of the Club.
Tim Fox
Re: DG505 G-CJZB Annual Inspection w/c 6th March
Well done to all involved and thank you for the huge effort.
-
Dave-McCormick
- Posts: 343
- Joined: Sat Feb 24, 2018 8:39 pm
- Location: Duns, Berwickshire
Re: DG505 G-CJZB Annual Inspection w/c 6th March
Tim,
Should we be concerned that the return spring on the belly hook was broken at replacement? The point of the replacement is to prevent the hook spring becoming inoperative. Sounds to me like an incident report to the BGA might be necessary.
Should we be concerned that the return spring on the belly hook was broken at replacement? The point of the replacement is to prevent the hook spring becoming inoperative. Sounds to me like an incident report to the BGA might be necessary.
Re: DG505 G-CJZB Annual Inspection w/c 6th March
Great Job and a huge thank you to the technical team!