Thursday, October 10, 2013

Failures, breaks, and solutions

During almost every venture into the field, something inevitably breaks. Try as we may to bring the most appropriate and robust gear with us, and to use it carefully, equipment fails during fieldwork in extreme environments for a variety of reasons: (a) it isn't quite up to what we ask of it, (b) it is simply worn out, and/or (c) it fails due to unforeseen stresses - such as getting dropped.

One of the challenges of gear problems during fieldwork is... solving them! Such tasks span the full spectrum from exasperating to fun, yet their outcomes influence the extent to which fieldwork objectives are met. A few approaches for mitigating gear and equipment failures include: (a) redundancy, in which multiple methods are planned - or equipment brought along - to accomplish the same task, (b) repair, usually requiring supplies and tools, and (c) substitution of a different piece of gear or a different approach.

During fieldwork on Quelccaya in July we were presented with an unusual number of equipment challenges, minor and major, solvable and not. Upon return we pondered, investigated, and resolved them in a variety of ways. Below are our 2013 gear challenges and their solutions or outcomes, in no particular order. In cases where the original manufacturer was contacted, note the variety of support (customer service) we received!
  • After more than a decade of faithful service, a Black Diamond Gemini headlamp must have been damaged during travel, for it was unresponsive when needed the first night at base camp. Neither changing batteries nor disassembling it revealed the problem, which may have been a broken wire within the insulation. A spare headlamp was borrowed from one of our guides, and ironically the Gemini was found on within a duffel late in the trip. The headlamp continues to function fine, but has been replaced and is now relegated to use closer to home.
  • An apparently faulty switch on one of the dual-frequency GPS receivers resulted in loss of some data from one of the base stations. This well-used unit has only LED lights to indicate functionality. Suspecting a potential power problem when the unit was deployed, we bypassed all connections between the GPS and power supply. This initially appeared to solve the problem, which we later learned did not. Although data were lost spanning several days, power was continuous through the most critical period when multiple base stations operated.
  • Continuing with power problems, a "powergorilla" portable power supply station (Powertraveller, Ltd.) came along to supplement aging laptop batteries. Although the unit had worked well on several previous trips within the past 2 years, it appeared dead upon plugging in the laptop. Strangely, it appeared to take a charge just fine via a "solargorilla," yet when disconnected it had no power. Powertraveller was contacted about the problem and agreed to replace the unit, despite expiration of the warranty. A new powergorilla will power a laptop and recharge mobile phone batteries on Kilimanjaro, later this month!
  • At the AWS, three problems developed in the year of autonomous operation. One was the complete failure of the transducer within one of the station's Campbell Scientific SR50 Sonic Ranging Sensors, a relatively uncommon event. These transducers are replaced annually, both to prevent such failures and to yield the cleanest possible measurements; without replacement however, the transducers sometimes last years. When one failed on Quelccaya in mid-May this year, 55 days before our field visit, almost all data were lost. This is why 2 sensors are used on all UMass stations, and replacement sensors with new transducers and desiccant are brought in each year, following careful lab testing. 
  • A second sensor problem at the AWS involved one of the Rotronic MP101A temperature and humidity probes. This was not a new issue and the equipment is not to blame, but is likely due to a combination of the technology used, intermittent ventilation of the radiation shield, and a relatively humid environment during the Quelccaya wet season. The probe which develops problems has been housed within a radiation shield which is intermittently ventilated by fan (2 of every 10 minutes), and under certain conditions ice crystals are hypothesized to grow during ventilation and then melt during the subsequent unventilated 8 minutes. Despite microscopic analysis of several probes by both Rotronic and Vaisala - which clearly reveals damage to the thin-film polymer - the problem with the humidity sensor has never been satisfactorily explained. So, during this field season the probe and shield were both eliminated!
  • The third AWS problem in 2013 was due to the fan motor on the shield referenced above, which allowed measurement of the fan revolutions. This ceased functioning at the end of March. The decision to remove the shield was not difficult, due to known radiation-loading errors with this shield design.
  • A new batch of "harsh-environment" cable ties was purchased for this fieldwork, in an effort to economize on well-proven Tefzel ties. In every attempted installation, the tooth which allows only one-way motion immediately broke; they may have been a defective batch. McMaster-Carr promptly refunded the cost of these.
  • To measure snowpit stratigraphy and sample depth, we have been using a Lufkin brand tape measure with a powerful spring to retract the tape into a housing. When blowing snow accumulated in the pit and buried the tape cartridge, a bit-too-much pulling caused the tape to detach, creating 8 meters of chaos. Replacing the tape was not possible in the field or lab, and an e-mail to Lufkin was unanswered.
  • Lastly, at some point during travel to or from Cusco the airlines broke the frame of a Mountain Hardwear rolling duffel (Juggernaut) - one which had endured numerous prior trips. This has always been a crucial piece of luggage, as it offers more protection for items than a soft duffel and rolls exceptionally well. Mountain Hardwear inspected the break - which was considered unusual - and quickly provided a new Juggernaut.
For forthcoming fieldwork on Kilimanjaro we will be ready for breakages and failures, as always, but we are hoping for considerably fewer than at Quelccaya. After all, there are always other types of gear issues, such as forgetting and loosing things, even though we try to avoid these as well!