Piper Meridian Aircraft Facts

There have been numerous upgrades to the Meridian fleet over time that potential owners should know. They are summarized briefly here for your benefit.

Gross Weight Upgrade

Beginning with Serial Number 157 in early 2003, Piper offered an upgraded gross weight capability for the Meridian. It added 242 lbs. to the gross weight of the aircraft to a maximum takeoff weight of 5,092 lbs. Based on individual aircraft weights, this upgrade provides a full fuel payload of 500-550 lbs., depending on equipment. It was achieved by adding vortex generators to the wings and rear horizontal stabilizer plus an upgrade of the main gear struts. Piper Aircraft allowed dealers who had existing Meridians in inventory at the time of the upgrade announcement to retrofit those aircraft. There are 15 of these aircraft in the fleet. Piper did not make the upgrade available to the rest of the earlier serial number aircraft and continues not to offer it in any kit. In late 2012, Cutter Aviation out of Texas established an STC for the gross weight upgrade (which costs approximately $60,000), which enables older aircraft to achieve the increased gross weight for the Meridian. This upgrade provides a significant increase in payload, which helps maximize range without reducing utility in passengers and baggage.

Fuel Temp Probe

Prior to the use of a fuel temperature probe, the Meridian was limited to an operating environment of -34° C in outside air temp. Unfortunately, it is common in the winter months for temperatures in the flight levels to quickly descend well below -34°C. While an aircraft may take off the ground in a normal outside air temperature, as it climbs the outside air temperature can rapidly drop below -34° C. When this happens, the Meridian must descend to a lower altitude, which usually results in a higher fuel burn and lower true airspeed.

Beginning in serial number 174, Piper began offering a fuel temperature probe internal to the fuel tanks with a digital readout on a display in the cockpit to measure the temperature of the fuel in the tanks. This update also incorporates a heated fuel return from the engine back into the fuel tanks. This fuel, not used in combustion, is returned to the main tanks after passing through the PT6-42A engine typically operating at over 600° C. This generally produces a temperature difference between outside air and fuel temperature readings on the cockpit display of +6 degrees after sustained flight in the flight levels. Of course, an aircraft departing from a field elevation or coming out of a heated hangar briefly before departure will also take longer for the fuel to cool as it climbs, which provides an additional delta between outside air and fuel temperature.

The result of this fuel probe installation is sustained flight in the upper flight levels (typically FL 270 and FL 280), which allows the pilot to maximize true airspeed and reduced fuel burn to extend range and reduce operating cost. It also provides the comfort of knowing that fuel will not be coagulating, leading to a dangerous high altitude flame out of the engine. This conversion was announced Sept. 23, 2005, in Service Letter 1090 and can be completed for earlier serial number aircraft by using Piper Kit # 767-380 (full components, SN 001-158) or Kit 767-381 (for SN 159-173 that already have the cockpit display installed but require the correct hoses). It usually runs about $15,000 installed. It is also important not to confuse this upgrade with two Piper Service Bulletins, 1077 and 1091, which makes changes to the oil-to-fuel heater which provides a thermostatic valve for correctly maintaining the proper temperature of the fuel entering the engine. This is primarily aimed at avoiding excessive temperatures, which can lead to reduced idle operating speeds.

Environmental Control System (ECS) Upgrade

This upgrade was announced in Service Letter 1104 on March 14, 2008. It was designed to minimize potential fluctuations in cabin pressure and improve the accuracy of the flow control pressurization sensor. The basic concept behind the upgrade was to reduce down the crossover tube’s diameter, thereby increasing the pressure and minimizing the work required by the subsequent parts in the system. This enabled a more accurate measurement of air flow and had less potential for deviations.

The upgrade was provided in two different kits. Kit #88417-002 replaces all parts with factory new components. Kit #88417-003 used overhauled parts and did not include the Mass Flow Sensor Assembly or the Mass Flow Controller, both expensive parts. These upgrades are no longer provided as kits but the key point to learn from the issue is that the new design is now standard. What this means is that when an older Meridian has an ECS component fail, and if that aircraft has not been upgraded to the new design, the owner or operator of that aircraft will be required to change out the components of the ECS system to reflect the new design. This change out can lead to an unexpected maintenance event approaching $10,000 inclusive of labor when perhaps only one part failed leading to the maintenance event. It is important then for potential owners of Meridians to verify whether or not this upgrade has occurred prior to buying a Meridian before model year 2008.

WAAS Upgrade

On Feb. 19, 2009, Piper announced via Service Letter 1115A the availability of a WAAS upgrade for the Meridian, also now offered as standard on new Meridians from the factory. This service letter provided for an upgrade to the STEC 1500 autopilot and the installed Garmin 430 navigators in existing Avidyne configuration. This required upgrade, to the Avidyne Software Release 7.1, called for the S-TEC 1500 autopilot controller to be sent back to Cobham (S-TEC) for reprogramming and the Garmin navigators to be upgraded by Garmin for WAAS.

Ironically, earlier Meridian aircraft were actually upgraded sooner as Cobham/S-TEC announced the availability of WAAS for Meggitt based aircraft (Service Bulletin 08-005R2, Oct. 3, 2008.) This upgraded the flight displays, the 1500 autopilot controller and also required that the installed GNS 530 navigators be upgraded as well. Of note, the S-TEC 550 (commonly known as the 55X) autopilot did not require an upgrade as its architecture did not require modification.

LED Light Upgrade

Piper announced on April 26, 2012, via Service Letter 1157, the availability of an LED light upgrade. Part Number 472-528 covers the Landing Light, Kit 88508-002 the Strobe and Position Lights, and Kit 88505-002 the taxi and recognition lights. These offerings provide more efficient and brighter LED lights as compared with standard factory lights while offering the longer life expectancy of the LED technology. This was very much a response to external competitors such as Lo Presti that had been providing, via STC alternative lighting to the factory lighting, primarily for main landing lights on the nose wheel. By providing these in kit form, Piper wisely enables owners to upgrade the lighting on the wing tips to take advantage of the newer technology without squandering their investment in the Lo Presti landing light.

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