The Duncan Download Blog: Business Aviation Advice & Observations

Contributed by Bill Walker, Turbine Engine Tech Rep.

Preventive maintenance will help reduce the operating costs of aircraft engines.

I was recently asked by a customer, “Is it possible to wash my Pratt & Whitney engine too much?” The operator considered his inquiry to be silly when, in fact, it’s a very valid question. In fact, it’s important to periodically clean your engine as a part of preventive maintenance. And, if you operate your aircraft in adverse environments, such as air pollution and salt-water exposure, it’s very important to increase your wash schedule. Here's why.

Reduce Corrosion

Chemical reactions with the fuel and heat can produce severe corrosion, which can be significantly reduced through regular gas path washing. Although corrosion is not covered by the Eagle Service Plan (ESP) or warranted by Pratt & Whitney Canada (P&WC), the company does allow for the customer to determine their own wash schedule giving consideration to their specific operating environment.

Improve Performance

A desalination wash uses water or water/methanol to remove salt and light deposits, but if the engine is experiencing a loss of performance, as indicated from Engine Condition Trend Monitoring (ECTM), a performance recovery water wash will be recommended. Cleaning agents are used to remove deposits that cannot be dissolved by a desalination wash. Pratt publishes a list of acceptable cleaning agents, including a formula they developed called WCT (2 parts Witconate HC59B, 4 parts Carbitol and 1 part Triethanolamine), in chapter 71 of the maintenance manual.

It is very important to observe the maintenance manual requirements of using methanol when the outside air temperature requires mixing with the cleaning agent or rinsing solutions. As a practice, Duncan Aviation does not perform a water wash in outside air temperatures of less than 0°c / 32°f.

Reduce Operating Costs

The answer to the original question is “NO.” Periodically, rinse the external portions of the engine and if you are flying in adverse environments, absolutely, increase your wash schedule. Preventive maintenance, especially when dealing with corrosion, will reduce the operating costs of the engines, the added expense of repairing corrosion and additional downtime.

Duncan Aviation is a Pratt & Whitney Authorized Service Center for JT15D, PT6, 300,500,600 series engines. For a complete list of our PW engine maintenance capabilities, technical support and service sales contacts, please visit www.duncanaviation.aero/engine/pw.php. 

Bill Walker serves as an Engine Tech. Rep. for Duncan Aviation-Battle Creek, specializing in CF34, JT15D, PT6A Turboprop, and PW300, 500 and 600 engines. His aviation career began in 1979.

Contributed by Leo Sawatzki, Engine Parts / Engine Sales Manager

In the past, when the economy was strong, aircraft operating budgets were larger and everyone requested new parts be put in their engines during major inspections. As the economy began to slow, operators scrambled to find lower-cost alternatives. Now, although we have experienced some recovery from the downturn, people haven’t forgotten and continue to seek the best value available.

That value can be found in reclaimed aircraft engine parts. Below are four reasons why you should consider reclaimed parts at your next major engine inspection.

1. Same Quality Performance

Reclaimed engine parts provide the same reliable operating service as new parts at a lower cost. They have been inspected, overhauled or repaired and then re-inspected. And finally, the parts that are declared viable for operation are tagged with an FAA 8130 dual release tag, accepted by both the Federal Aviation Administration (FAA) and the European Aviation Safety Agency (EASA), and put into inventory. 

2. Lower Cost

New aircraft engine parts are made out of rare and exotic metals that are becoming more difficult to find. These metals are a dwindling resource and are becoming more difficult to find; causing the cost of new engine parts to rise significantly. During a major engine inspection, many parts are replaced. Using reclaimed parts will keep inspection costs down without sacrificing quality or safety.

3. Increased Aircraft Life

As an aircraft ages, the cost associated with operation and maintenance of older engines begin to represent a larger portion of the aircraft’s overall cost of operation. Reclaimed parts are a lower-cost alternative that allows aircraft to continue to provide valuable flight services to their operating companies for longer periods of time.

4. Reduced Environmental Impact

The entire aviation industry (commercial, business and general aviation) relies upon rare exotic metal alloys such as titanium, waspaloy, hastelloy and inconel to manufacture new aircraft engine parts because of their ability to withstand high heat and their strength-to-weight ratio that is necessary for flight. Reclaiming good, used engine parts and reintroducing them back into service is recycling at its very best. No more precious metals are taken out of the earth and very little, if any, machining or chemical applications are necessary in order to return these parts to service in another engine.

As an authorized OEM facility, Duncan has been buying, selling and exchanging engines and APUs for more than 20 years and is the only Honeywell-authorized facility to offer this lower-cost alternative. Learn more about using reclaimed engine parts as a low-cost alternative.

Leo Sawatzki is Duncan Aviation’s Engine Parts Sales Manager located in Lincoln, NE. He specializes in locating hard to find aircraft engine parts. His aviation career began in 1968.

Contributed by Jason Duhs and Dennis VanStrien, Airframe Service Sales Reps.

Aircraft aftermarket programs offer some very real advantages to business aircraft operators, especially when it comes to budgeting. Many of these programs are purchased after the manufacturer warranty expires for the aircraft. While it’s unlikely that an aftermarket program would be overlooked by a service provider, it’s always a good idea to talk about which programs apply to your aircraft and your parts ordering preferences.

1. Identify Maintenance Programs

Always provide a list of aftermarket programs that apply to your aircraft. Service providers should always research or request aircraft program information before asking for your signature on a maintenance service agreement. However, in cases where service sales representatives might be out of the office, this step might be overlooked by well-intentioned support staff.

Providing a list of applicable programs will help a service center coordinate services appropriately. Providing access to the aircraft’s maintenance tracking service and logbooks beforehand will also help a service provider identify service bulletins or other services that might be required for your aircraft.

2. Ask About Warranty Coverage for Avionics Retrofits

Ask about the material, equipment and workmanship warranties that cover an avionics retrofit. Some equipment is warranted for one year, others for five years. If you opt for serviceable equipment (used equipment) to be installed, there’s no equipment warranty.

It’s easy to forget when an avionics equipment warranty will expire. When it does expire, operators may want to consider an avionics service plan like the Honeywell Avionics Protection Plan (HAPP) or Rockwell Collins’ Corporate Aircraft Service Program (CASP), depending on what system was installed.

Depending on the service provider, workmanship can be warranted for as long as three years. For example, Duncan Aviation provides a three year / 1500 hour warranty on avionics installations.

3. Clarify Parts Ordering Preferences

Tell your service provider how you want to handle parts ordering. This helps ensure that any covered parts are ordered by the right people, through the correct venues. Some operators prefer to order their own parts, others leave it to their service center. Make sure your sales representative and lead technician understand your preferences before work begins on your aircraft.

Duncan Aviation provides support for several aftermarket programs for business aircraft. Engine programs we support include Jet Support Services, Inc. (JSSI), Honeywell’s Maintenance Service Plan (MSP) and MSP Gold, Pratt & Whitney Canada’s Eagle Service™ Plan (ESP®), Cessna’s Power Advantage and Williams’ Total Assurance Program (TAP). Avionics programs we support include HAPP and CASP. Parts and consumables programs include Cessna’s ProParts (part of Power Advantage) and Bombardier’s Smart Parts and Smart Parts Plus. We also support Embraer Executive Care (EEC) and Raytheon’s Support Plus.

Please contact a Duncan Aviation rep. for more information about the aircraft aftermarket programs we support.

Jason Duhs serves as an Airframe Service Sales Rep. at Duncan Aviation’s Lincoln, Neb. (LNK) facility, specializing in Citations and King Airs. He began his aviation career in 1996. Dennis VanStrien serves as an Airframe Service Sales Rep. at Duncan Aviation’s Battle Creek, Mich. (MI) facility, specializing in Citations. His career in aviation began in 1976.

Contributed by Chuck Zahnow, Airframe Tech Rep

The normal engine startup sequence for Citation 560XL aircraft removes power from the avionics system, causing it to drop offline. The reason for this is the avionics are isolated from the start system. SB560XL-24-14R2 allows the avionics to stay online by using the APU generator during engine start.

This service bulletin (SB) is a really great modification for the airplane, but there are still aircraft that have not been modified and time is running out. Cessna warranty covers all affected aircraft until February 2012. If the SB has not been accomplished yet, it is not too late.

The modification requires removal of the aft J-box and access to the aft baggage floor and cockpit PCB box. The best option for this to be done is at a major inspection, since it won’t add downtime and the inspection improves access to these areas. If the SB is done alone, it will take about one week.

If there is not a major inspection to be done prior to February, that is not an issue. We have been able to get this done and get it covered by warranty, including the hours of access.

Affected serial numbers include:

• 560XL: 5002-5372 (if APU is installed)
• 560XLS: 5501-5799 (all)

If your aircraft is affected and you haven’t done this SB, I strongly recommend you get it done before the warranty expires.

Duncan Aviation is a Cessna authorized service center for Citation 500 and 600 series. For a list of our Citation service capabilities, technical support and service sales contacts, please visit www.DuncanAviation.aero/airframe/citation.php.

Chuck Zahnow serves as an Airframe Technical Representative at Duncan Aviation’s Battle Creek, Mich. (BTL) facility, specializing in Citation and Hawker aircraft. He began his career in aviation in 1996.

Contributed by Lanny Renshaw, Assistant Manger Turbine Engine Services  

There are many reasons that your TFE731 engine may be leaking oil. The hardest part is determining where it is leaking and what to do about it. The following is a list of the most common places you will find oil leaks and their causes.

Oil Leaking from the Breather Pressurizing Valve (BPV)

If there is oil leaking from the BPV after the engine has been shutdown and idle for a day or so, the oil tank may have a cracked internal tube that is allowing oil to flow out of the tank and into the accessory gearbox. When the accessory gearbox is full, the oil will begin to run out the BPV.

If your engine has just come out of its Compressor Zone Inspection (CZI) however, verify that oil pump P/N 3060785-XX is installed. Oil gets trapped in the oil coolers or other areas and moves through the oil pump, filling the accessory gearbox and eventually leaking out of the BPV. This happens on the RH engine installations and sometimes on the #2 position on the F50/900s.

Oil Leaking in the Third LPT/Exhaust Area

If oil begins to pool in the exhaust nozzle area after engine shutdown, the cause may be one of the following:

1. Over-servicing the engine oil level
2. Defective #6 carbon seal/rotor
3. Oil pump P/N 3071949-11 or 3060785-X on RH engine installations allow oil to get trapped in the oil coolers and fill up the #6 bearing area. This oil will eventually run out the #6 carbon seal and down the Third LTP blades. This can be easily fixed with the installation of oil pump P/N 3071949-12, which has a redesigned regulator allowing oil to flow back to the oil tank.

Oil Leaks in the Fan Inlet Area

There are several reasons that oil will leak into the Fan Inlet Area. Here are some of the more common:

1. #1 carbon seal leaking—oil will be running down the fan blades.
2. #3 carbon seal leaking— oil will be running out of the Compressor Inlet Stator.
3. A cut o-ring on the Fan Support Housing or some other areas in or around the Fan Inlet area.

Oil Leaks from the Hot End

If oil is leaking from the hot end, it might be one of the following:

1. N1 Monopole leaking on the cover plate or the cover plate itself is leaking.
2. Loose #6 oil pressure and/or scavenge lines.
3. Oil leak coming from the oil cooler area.

 Duncan Aviation holds service authorizations for Honeywell TFE731-2/-3/-4/-5/20/40/60 Major (MPI) engines at its full-service facilities in Lincoln, NE (LNK), and authorized line services in Battle Creek, MI (BTL). Our TFE731 engine program has been in place since 1980, and we have assembled teams with some of the most talented engine technicians in the industry.

Lanny Renshaw, Assistant Manager of Turbine Engine Services in Lincoln, NE (LNK), manages Duncan Aviation’s modern 20,000-square-foot facility with 12 separate engine bays dedicated to support of the Honeywell TFE731. He started his aviation career in 1982.

Contributed by Lanny Renshaw, Assistant Manager Turbine Engine Services

When faced with an oil pressure squawk, check the Breather Pressurizing Valve.

Many factors will cause a low or high oil pressure indication on TFE731 engines. One of the more common causes is a faulty Breather Pressurizing Valve (BPV). The following are two scenarios that will lead you to this conclusion.

Oil Pressure Rises During Decent

If the crew reports normal oil pressure at altitude but the pressure rises as the aircraft descends, the most probable cause is the BPV is stuck closed. At sea level, the valve should be open at least .07 in. A defective bellows will cause the valve to be closed on the ground. With a strong light, visually check the BPV. If it is closed, replace the BPV.

Oil Pressure Drops During Climb

Oil pressure that is normal below 27,000 ft but drops as the aircraft climbs higher is another indication the BPV is not closing. Remove the BPV and push on the bellows. They should not move. If you are able to move them, replace the BPV. If the bellows feels normal, swap with the opposite engine. If the squawk is still present, contact your TFE731 Service Center.

TFE731 Engine Oil System Presentation

I will be giving an in-depth presentation on the entire TFE731 Oil System at the Duncan Aviation Intelli-Conference on Sept. 22nd in Teterboro, NJ. My presentation will include additional steps to troubleshoot oil pressure problems, an overview of the oil system schematic and troubleshooting oil leaks. The class is free and attendees will get Inspection Authorization (IA) renewal credit. Register now to reserve your seat!

Duncan Aviation holds service authorizations for Honeywell TFE731-2/-3/-4/-5/20/40/60 Major (MPI) engines at its full-service facilities in Lincoln, NE (LNK), and authorized line services in Battle Creek, MI (BTL). Our TFE731 engine program has been in place since 1980, and we have assembled teams with some of the most talented engine technicians in the industry.

Lanny Renshaw, Assistant Manager of Turbine Engine Services in Lincoln, NE (LNK), manages Duncan Aviation’s modern 20,000-square-foot facility with 12 separate engine bays dedicated to support of the Honeywell TFE731. He started his aviation career in 1982.

Contributed by Mike Bernholtz, Turbine Engine Services Sales Rep.

December 31, 2011, is the last day to comply with the FAA Airworthy Directive (AD) 2005-05-15. This AD requires the replacement of low pressure turbine LPT stage 1 discs for affected TFE731-3, -3A, -3AR, -3R, -3B, and -3BR series engines.

Delayed Inspection May Mean Delayed Capacity & Parts

According to the Honeywell website, there has been a low compliance rate for this AD since it was issued in 2005. They are encouraging all operators who are affected to contact an authorized service center immediately to schedule the inspections and part replacements.

Consequently, at Duncan Aviation, we believe as the deadline gets closer, the demand and lead time for parts will increase significantly. There is also a real possibility that engine maintenance shops will not have the capacity to handle these requests on a 'last minute' basis.

Affected TFE731 Engines

All TFE731-3, -3A, -3AR, -3R, -3B, and -3BR engines installed on one of the following aircraft models must have this AD performed before 2012.  

• Learjet 55   
• Hawker 400, 600,700
• Westwind I and II (IAI 1124)
• Falcon 50
• Jetstar
• Astra
• Citation III/VI
• Sabreliner

This AD does not apply on engines that have had the 3C or 3D upgrade.

Engines that are still running a LPT1 disc part, numbers 3072070-All, 3072351-All, 3073013-All, 3073113-All, 3073497-All and 3074103-All, require replacement prior to 2012.

To further emphasize the importance of complying sooner rather than later, Honeywell has issued a Service Information Letter (SIL). If applicable, Honeywell has a pricing program for the replacement of the disc and the LPT1 blades.

Duncan Aviation is a Honeywell Authorized Service Center and operates a 20,000 square foot engine maintenance shop dedicated to the support of TFE731 engines.

For more information about this AD, contact Shane Heier, Duncan Aviation's Honeywell Engine Tech Rep. To schedule this inspection and parts replacement, contact Engine Maintenance Service Sales.

Mike Bernholtz is a Turbine Engine Services Sales Rep specializing in Honeywell TFE731 inspection and maintenance services. His aviation career began in 1989.

In March of 2010, the first blog post for the Duncan Download was published. Today, in honor of our 100^th blog post and the success of all of Duncan Aviation, we are sharing with you a list of 100 achievements, milestones and down-right cool things to brag about that have occurred at Duncan Aviation since the first post.

Celebrate with us.

Company

1. 55^th anniversary of company founding observed
2. 168,377 square feet of leather goods purchased for new aircraft interiors at BTL and LNK
3. 5,457 Component Solutions customers served worldwide
4. 7,259,089 gallons of Jet A fuel sold at Kalamazoo, MI (AZO), Battle Creek, MI (BTL) and Lincoln, NE (LNK)
5. 133,864 gallons of Avgas sold at AZO, BTL and LNK
6. 1,652 aircraft delivered out of maintenance at BTL, LNK and Provo, UT (PVU)
7. 615 business aircraft maintenance road trips to seven countries from all locations
8. 160 business aviation conventions and events attended by Duncan Aviation
9. 1,342 AOG engines returned to service in the field by Engine Rapid Response
10. 1,810 engines returned to service out of BTL and LNK
11. 204 TFE731 MPIs performed in LNK
12. 22 Pratt & Whitney Hot Sections performed in BTL
13. 126,077 Fed Ex packages shipped and received totaling 3,709,389 pounds
14. 258 aircraft interior refurbishments performed in BTL and LNK
15. 93 business aircraft painted at BTL
16. 141 aircraft Wi-Fi solutions installed per a STC at all locations; majority under a Duncan Aviation STC
17. 157 in-flight internet solutions installed. Duncan Aviation is the market leader
18. 30 WAAS/LPV systems installed at all locations
19. 25 Falcon winglets installed at BTL and LNK
20. 52 Falcon dry bay mods completed at BTL and LNK
21. 24 Gulfstream water line ribbon heaters upgrades (ASC 469/173) performed
22. 63 business aircraft prebuy evaluations performed in BTL, LNK and PVU
23. 624 aircraft landing gear legs overhauled
24. 1,851 aircraft batteries overhauled or reblocked
25. 13,710,410 aviation parts sold
26. 345,000 Component Solutions customer service calls
27. 11,360 aviation tools calibrated
28. 2,355 NDT inspections performed
29. Secured full contractual logistic support for the Mexican Navy Lear program 
30. 4 year F20 contract renewed with Royal Norwegian Air Force
31. 13,800 additional labor hours contracted with Offutt AFB in OMA
32. 1 year contract renewed with Egyptian Air Force
33. 2 L60 Flight Inspection Aircraft delivered to the Malaysian Department of Civil Aviation
34. Signed contract for Egyptian Air Force G3 Hush Kit installation
35. 62 customer dinners at BTL and LNK
36. 10 customers serving on Duncan Aviation’s Customer Advisory Board
37. 10 members of Duncan Aviation’s Board of Advisors
38. 10 customers to serve on the new Duncan Aviation European Customer Advisory Board

Facilities

39. 25^th anniversary of Avionics Satellite Network observed
40. 10^th engine Rapid Response location opened in Seattle, WA
41. 4 new Satellite Avionics locations opened
42. 3^rd aircraft maintenance facility opened in Provo, UT, with Bombardier (Challenger/Learjet) Authorization
43. 1 new paint hangar construction project breaks ground at LNK
44. AHA Fit Friendly Platinum awarded to BTL and LNK
45. Regional Health Alliance Workplace Wellness Award presented to BTL
46. 2010 United Way Corporate Volunteer Company of the Year presented to BTL

Authorizations & Certifications

47. 30th anniversary of Honeywell Authorized TFE731 Major Service Center
48. 51 revisions approved for existing STCs
49. 8 type design amendments approved for existing STCs
50. 16 new STCs issued
51. 7 Wi-Fi STCs issued in seven airframes, including the first Wi-Fi STC in the Citation 750
52. 6 WAAS/LPV STCs issued, including the first Learjet 31A, the first Honeywell NZ-2000 FMS in a Falcon 900B and Challenger 601-3A
53. 6 foreign certificates renewed by audit
54. 5 PMA supplements added
55. 4 interior alteration STCs issued
56. 1 FIS STC issued
57. First iPad integration for Cabin Control in Falcon 900 certified, iCabin service mark earned
58. PVU named Embraer Authorized Service Facility for Phenom 100, 300
59. New authorizations added to China CAAC Repair Station Certificate
60. Named exclusive repair service provider for Avidyne Legacy Display System

Private Flight Services

61. Launched Safety Management System
62. 11 aircraft owned, managed and operated
63. 2,800 flight hours flown by 13 Duncan Aviation pilots
64. 1,000,000 miles flown by 13 Duncan Aviation pilot

Team members

65. 20^th anniversary of Duncan Aviation Project Manager Services
66. 10^th anniversary of Engine Rapid Response AOG Services
67. 475 military veterans serving at Duncan Aviation
68. 312 new Duncan Aviation employees hired
69. 230 technicians attended OEM factory training for 14 airframe or engine types
70. 12 Duncan Aviation employees retired
71. 217 employees volunteered for the 2010 National Special Olympic Games in Lincoln, NE
72. 35 Duncan Aviation employees employed at least 25 years inducted into Silver Wings Club
73. 77 babies born to Duncan Aviation families
74. 15 employees serving on business aviation industry boards
75. 13 employees qualified in or expanded responsibilities as Unit Members under ODA designation
76. 20 multilingual representatives located in 14 countries
77. 1 new European Regional Manager
78. 2,746 vacation hours donated to fellow coworkers in need
79. 2,327 items of food donated to local food programs
80. United Way Corporate Volunteer Company of the year for 2010 (BTL)
81. $177,981 raised for United Way at LNK, BTL and AZO
82. Generously supported many other local charities in every community  

Informational Resources

83. Job status tracking launched for myDuncan.aero
84. ADS-B Straight Talk book published.
85. Field Guides published about business aircraft Issues
86. The Duncan Download Blog launched
87. “Understanding WAAS/LPV” Video Series launched
88. 73 Duncan Intelligence articles published
89. 72% increase in new visits to www.DuncanAviation.aero
90. Updated company logo designed and introduced
91. Company video, websites and brochure launched in five languages
92. Web directory expanded to include profiles of customer contacts
93. WAAS/LPV calculator launched to demonstrate technology value
94. Inflight internet system selection tool launched

Additional Service Offerings

95. Bombardier Global Service capabilities expanded
96. Phased Interior Maintenance program launched
97. Interior Program with 14-Day Downtime Guarantee launched for Learjet and Citation models
98. Chrome-free paint process launched
99. New avionics capabilities for Avidyne Flightmax indicators, ELTA and Socata ELTs
100. Earth-friendly interior materials selected for interior refurbishments

As a business aircraft owner/operator, Chief Pilot or DOM, you have orders to cut expenses and come in under budget. That makes it very tempting to go with the maintenance facility offering the lowest bid. However, without fully understanding exactly what each bid includes—or more importantly does not include—going with the lowest number may have the highest cost when the final bill arrives.

After weighing the hard costs of the project and making sure the quotes provided are comparing like products and services, go beyond the bid number and properly compare each MRO.

Identify your priorities and get the answers to these questions.

1. What is their plan to meet your downtime requirement?
2. How much experience do they have performing your required maintenance or modification?
3. What is their stated warranty and what does it include?
4. What are the hidden charges? engineering services, interior R&R, consumables?
5. Are they an Authorized Service Facility / Authorized Dealer?
6. How are unexpected squawks and discrepancies communicated?
7. Will factory-trained technicians be working on your aircraft?
8. Do they have an FAA approved drug and alcohol prevention program?
9. How much insurance will be protecting your aircraft while in their hangar?
10. How will you approve squawks and discrepancies if not on-site?

Use this MRO Comparison Worksheet as a tool to compare your top service provider candidates side-by-side. Key points are identified to more easily find and compare the strengths and weaknesses of each organization.

Compare up to three MROs using the MRO Comparison Worksheet.

Contributed By Dennis VanStrien, Airframe Service Sales Rep

Mobile aircraft service units—like Duncan Aviation's interior SWAT, AOG parts and Engine Rapid Response Teams—offer on-site cleaning, AOG support and even major inspections. 

Mobile service units are in the headlines a lot these days. Most of the big aircraft service names have them and there are also a lot of smaller operations throughout the United States. They offer everything from cleaning to AOG emergencies to engine changes and even major inspections.

So, how do you know when mobile aircraft service is a good option for you? Here are three things to consider:

1. Downtime

Sometimes a road team will be able to solve a problem faster than you can, and can reach you in a time frame that may compete with a full-service facility's onsite availability.

This is true for troubleshooting and AOG parts situations. You can get the team and the parts to your location in relatively short order and be back in the air in no time. However, for larger jobs, it may take a road team longer than a full team at a service center. Two or three guys working dozens of labor hours will just take longer than five to six guys working an inspection on round-the clock shifts.

2. Cost

Using road teams spares you the cost of moving your airplane to a full-service facility, and for someone to travel with it to watch over the maintenance. A mobile team can be a good solution for an in-house team that needs a day or two of technical or heavy help, but can handle the rest of the inspection on their own.

However, road teams cost more. You are paying for their time, door-to-door service and in many cases their expenses. Convenience costs more.

3. Unforeseen Complications

What if an inspection uncovers something that needs more time, tools, parts or expertise to fix? The short answer is you are most likely in for more downtime. For instance, a cracked window. A repair in the field would extend the downtime, while a repair at a full-service facility would not.

So, consider your options and choose wisely. Sometimes service from a professional team in your hangar can be a real benefit. And sometimes it's just better to take your aircraft to a full-service facility. The great news is you have the choice!

Dennis VanStrien is an Airframe Service Sales Rep at Duncan Aviation's Battle Creek, Mich. facility, and specializes in Citation aircraft. He began working in aviation in 1976.