Gulfstream Spring 2003

• Transformer Rectifier Cooling Fans
• Winglet Attach Hardware
• Technical Evaluations
• The Value of Paint, Plan For Protection

Transformer Rectifier Cooling Fans

— Jim Overheul

We have noticed a increase in D.C. model Gulfstreams arriving with the fixed frequency A.C. inverter transformer rectifier (T/R) fans inoperable. In a few cases the fan was observed with backward and reduced airflow.

In a case such as this, there will be no cockpit indication of a failed fan, since the 200 degree Fahrenheit overheat thermal switch is dependent on proper air flow to sense an overheat condition [(T/R HT) GII, GIIB], [(Inverter HT) non-VSCF GIII]. In fact when the cooling fan has failed, the warmest end of the T/R is farthest away from the thermal switch.

For example, after twenty minutes of ground operation on a 75 degree day the T/R case temperature can exceed 165 degrees Fahrenheit while the thermal switch is only sensing 85 degrees Fahrenheit. A properly working T/R will typically see a case temperature increase of only 5 degrees Fahrenheit above ambient temperature.

We recommend checking the T/R cooling fan periodically to optimize performance and reliability. Remember, when checking the T/R fan, D.C. external must not be powering the aircraft and the associated alternator bus for that T/R must be powered.

Winglet Attach Hardware

— Jim Overheul

A GIIB recently visited Duncan Aviation to perform CMP cards 575002 and 575003 (winglet attach hardware inspection). This inspection was being tracked as a 24 month recurring inspection by CMP because ASC 507 was not shown in compliance.

Removal of the sealant revealed the hardware installed was corrosion resistant (CRES). Logbook research showed the CRES hardware was installed per Gulfstream Aerospace service engineering drawing number SE35809903. Installation of the CRES hardware meets the requirement for a 144 month recurring inspection.

Please contact Jim Overheul for more information on how a little research and technical experience could save you time and money on your next inspection.

Technical Evaluations

— Doug Donahue

Duncan Aviation can provide Technical Evaluations for customers interested in purchasing a pre-owned GII, GIIB, GIII, or GIV aircraft.

A Technical Evaluation is an evaluation of the entire aircraft to include research of log books for inspection status, ADs, ASCs, CBs, STCs, alterations, existence and accuracy of life-limited items. Please contact Doug Donahue at 800.525.2376 for more info.

The Value of Paint, Plan For Protection

— George Bajo

Our current economy is a catalyst for the exchange of aircraft and new paint is often a differentiator in the decision-making process. If you are considering buying or selling an aircraft, consider the condition of its paint. An aircraft kept in a quality coat of paint is less likely to develop corrosion. For this reason, aircraft should be stripped, inspected and repainted by a reputable aircraft paint facility every five to seven years.

Paint technology has improved considerably in recent years. The new High Solids (HS) primers and paint have evolved into excellent products with proven performance on all surfaces, including composites. Flexible agents in HS paint and primers, combined with skilled paint technicians, ensure a longlasting, top-quality finish and maximum protection for your aircraft.

Also consider that inferior or old paint can cause electrical problems affecting comm radios and navigation receivers. In addition, many aircraft manufacturers' "continuing maintenance instructions" for RVSM aircraft stress that the paint around the static ports needs to be kept in "new condition" with no paint chips allowed to disrupt the airflow over the static-sensing areas, which could cause altitude errors.

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