FAQ

A. General Questions

A1 - How can I get more information about the WALTER engines?
You can address WALTER ENGINES a.s. , or call Marketing Manager (+420) 602 643 547 and ask for the information brochure called WALTER M601 Turboprop engine Information. This information is available in printed and electronic form. The pdf file can be sent to you by e-mail. Specification sheets are also available for the various models of the M601 Engines.
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A2 - How can I get more information about WALTER production capabilities?
You can address WALTER ENGINES a.s. , or call Marketing Manager (+420) 602 643 547 and ask for information brochures. This information is available in English in printed and electronic form.
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B. Questions related to aircraft engines

B1 - What is TBO of M601 engine?
TBO of M601 depends on the engine model.
The TBO requirement are set based on flight hours, operating cycles and calendar time. If the engine passes a limit in terms of hours or equivalent cycles it must be returned to an authorized Walter M601 repair facility for overhaul.
If the calendar time limit is reached and the engine still has hours and cycles remaining prior to overhaul, the engine may be sent to the overhaul facility for Shop Revision to extend the calendar life or for overhaul. Shop revision restores the full calendar life, but does not change the engine status in terms of hours and cycles. Example: If the engine has 900 hours and 1500 cycles till overhaul, after a normal Shop Revision the cycles and hours remain unchanged and the full calendar limit is re-instated.
B2 - I have purchased a new M601 engine. The engine logbook shows a shorter calendar life than published in some of the Walter Engines documents. Can my engine be operated to the published calendar limit?
This discrepancy is caused by the way the engine was certified with our certifying authority, the CAA. The Calendar limit of any M601 is currently 8 years. Your engine can be operated to the full 8-year calendar limit using the field inspection processes defined in the engine Maintenance Manual. The two mandatory inspections are necessary at the 5th and 7th year of operation. The first inspection after 5 years extends the calendar life of the engine by 2 years and the inspection at 7th year extends the calendar life one additional year. These inspections include borescopic inspection of internal parts, replacement of o-rings and other rubber parts, performance and operational checks. The inspection requires only a few man hours by a Walter qualified maintenance engineer and it is accomplished with the engine installed on the aircraft. The calendar limit is then extended by a logbook entry noting approval to continue the engine in service. Your logbook shows the calendar life till the next inspection or overhaul.
B3 - When I look at the M601 engine data sheets, the weights shown are heavier than similar competing turboprop engines. What is the real weight difference?
Yes, according to the data sheets the difference in mass seems to be higher than for other engines of similar powers. WALTER a.s. shows the data of engine as it is delivered including all the devices included with the standard engine. The WALTER M601 is delivered fully equipped with most of the basic accessories necessary for operation of the engine. Many of these accessories are not included with our competitor’s engines. This is why the M601 appears to be heavier. The M601 requires less oil and includes more accessories in the basic weight, which decreases the installed weight difference. If you compare the installed engine weight of equally equipped engines, including Oil and accessories , the M601 is about 20 pounds heavier than the competing engines.
B4 - Can you explain how optional bulletin "Cancellation of service life limits and of fixed number of overhauls at all WALTER M601 engine models" dated September 5, 2002 influences the TBO of the engines? Does this mean the flight cycle limit was cancelled?
This is a misunderstanding caused by the translation of the wording from the Czech language to English. This bulletin addresses an old Life Limit that has been removed and does not address the TBO intervals.
When first introduced the M601 was approved with an ultimate Life Limit. The engine was limited to being overhauled only two times. When the engine reached it’s 3rd Overhaul it was considered un-airworthy. The mentioned bulletin states that this Overhaul Life Limit has been cancelled and now there is no limit in terms of number of times the engine can be overhauled.
Time between overhauls is not affected by this bulletin The applicable Maintenance Manual and Engine Logbook for your engine should be used to determine the TBO and when maintenance is required.
B5 - In the logbook of our M601E engine manufactured 1993, overhauled 1997, the TBO is given to be 2000 hours. In your promotional materials about M601E-11 engine I have read the TBO is 3000 hours. Is this a new TBO applicable on our M601E?
Engines manufactured after January 1st, 1998 any new M601E series engine (i.e., M601E, E-11 etc.) have been manufactured with hardware applicable to the TBO of 3000 hours. Overhauled engines may have been overhauled for a TBO of 2000 hours or - if upgraded during overhaul – they may have a 3000 hour TBO. Your engine can be upgraded during the next overhaul to the status of 3000 hours TBO.
There are following options of overhauls of original (2000 hours TBO) M601E/E-11 engines:
2000 hours 2250 equivalent cycles (standard)
Following upgrade options are available at the time of Overhaul for additional costs:
2000 hours 4000 equivalent cycles
3000 hours 3300 equivalent cycles
3000 hours 6600 equivalent cycles
B6 - I have M601D, can you upgrade it the M601E Model?
We are sorry, but even though on the first view basically all M601 engines look very similar, the internal differences between the M601D and M601E are extensive. The costs associated with the upgrade of engines from any model to different configuration (e.g., from D to E or from E to F) are not considered economically acceptable. You may wish to trade your engine for a later mode and Walter can assist you with an exchange.
B7 - I have seen an advertisement mentioning some problems associated with the operation of the M601 in arctic operations.
No, this is a rumor started by our competition. The M601 engine was designed from the very beginning to operate in the extremely cold conditions in Siberia where they have been in service for more than 25 years with no problems. M601E-11 is certified for ground start in temperature ranges of –50 up to +40 deg C ( down to – 20 deg C without engine preheating, down to –50 deg C with engine preheating). The absence of fuel nozzles and the benefit of an electronic start controller provides one button starting to minimize starting difficulties in any climatic conditions.
B8 - I purchased an engine from someone else and it has no logbook, can Walter produce a new logbook and will Walter Overhaul the engine?
The logbook duplicate can be released only in in case that the original logbook was lost or destroyed if the engine is fully airworthy (incl. calendar life in the moment of duplicate production). To accomplish this, we need: the Engine serial number, number of hours and cycles flown since the last repair, spoiled original logbook (if it exists), or some evidence that the original logbook does not exist or was destroyed or stolen (police protocol about theft, accident or other). The logbook duplicate will be filled in using the data available from company production records.
Yes, we can overhaul such an engine, but since we do not have appropriate data about the previous service life, we will assume the most unfavorable cases and all life limited parts will be exchanged. This will result in a higher than normal Overhaul cost.
B9 - Who can repair my engine?
Routine maintenance is relatively simple and can be accomplished using a normal mechanics license. Scheduled Inspections require a Mechanic who has attended the Walter one week type maintenance training course. This type of maintenance Available from any WALTER a.s. installation center. Other line maintenance is provided by WALTER a.s. European staff, by the staff at WALTER America or WALTER Russia. Heavy maintenance up to and including shop revision can be accomplished by WALTER America. Overhaul requires the engine to be returned to the WALTER ENGINES a.s. shop in the Czech Republic. Additional Major Service Centers are being added in other parts of the world.
B10 - Does Walter have engines available for rental if my engine fails and how long will it take to repair my engine?
Yes, we have prepared engines for AOG situations. These engines are provided under friendly conditions if the requirement for repair of your engine was the fault of Walter, of course you have to cover the operation costs incl. reserve for scheduled maintenance.
B11 - I am looking to purchase a Walter M601 engine, how much fuel will the engine use?
Fuel consumption depends on the specific engine model, flight conditions, power used and characteristics of individual engine installation. Basic fuel burn infomations available in the WALTER M601 Turboprop engine Information brochure. WALTER ENGINES a.s. provides basic specific fuel consumption data for individual engine models on request, please address your question to Marketing Department.
B12 - What is the reliability of the Walter M601 engine?
WALTER a.s. is certified aircraft engine manufacturer. The reliability of the M601 engine is carefully documented. Reliability data for the M601 engines are comparable with that of other turboprop engine manufacturers of the same power ranges. For updated statistical data please ask Marketing of WALTER ENGINES a.s.
B13 - I am planning to purchase an M601 from an individual, what should I look for before purchasing the engine?
We recommend you to ask for the WALTER M601 Turboprop engine Information brochure, where you receive basic information about the engine. You need to examine the engine logbook to determine the hours and cycles to TBO along with the calendar life. If the engine is installed in an airplane you should ask for a demonstration run to verify engine performance. As a final step in you decision process you may wish to ask WALTER to check the status of the engine through factory records. For this you should contact Marketing of WALTER ENGINES a.s. with engine serial number.
B14 - Can my A&P Mechanic perform the 300-hour inspections required by the Maintenance Manual?
To assure properly perform the 300-hour inspections your mechanic should attend special maintenance training. For more information please see Maintenance Training page.
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B15 - Can I burn Diesel Fuel in my Walter M601 Engine?
No, diesel fuel is not approved for the M601 engines. Use of a un-recommended fuels may cause serious damages to the Fuel Control Unit seals which could result in fuel control problems and loss of power in-flight.
B16 - What is the cost of operation of the Walter M601?
Since this depends on many factors, it is not possible to give specific figures. Basically the economy is depending on costs of maintenance, costs of fuel and other additional costs like insurance. Routine Maintenance costs are very low due to the very low maintenance requirements. Depending on specific engine model and flight envelope, fuel consumption is comparable with the other turboprop engines in the same power class.
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